diff --git a/docs/guide/datastore.ipynb b/docs/guide/datastore.ipynb
index 7d40930..c3980a0 100644
--- a/docs/guide/datastore.ipynb
+++ b/docs/guide/datastore.ipynb
@@ -4,6 +4,7 @@
    "cell_type": "code",
    "execution_count": 1,
    "metadata": {
+    "collapsed": true,
     "nbsphinx": "hidden"
    },
    "outputs": [],
@@ -24,6 +25,7 @@
    "cell_type": "code",
    "execution_count": 2,
    "metadata": {
+    "collapsed": true,
     "nbsphinx": "hidden"
    },
    "outputs": [],
@@ -383,8 +385,10 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 7,
-   "metadata": {},
+   "execution_count": 3,
+   "metadata": {
+    "collapsed": true
+   },
    "outputs": [],
    "source": [
     "import sys\n",
@@ -415,7 +419,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 9,
+   "execution_count": 6,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -428,11 +432,11 @@
     "fs.source.filters.add(f)\n",
     "\n",
     "# attach multiple filters to FileSystemStore\n",
-    "fs.source.filters.update([f1,f2])\n",
+    "fs.source.filters.add([f1,f2])\n",
     "\n",
     "# can also attach filters to a Source\n",
     "# attach multiple filters to FileSystemSource\n",
-    "fs_source.filters.update([f3, f4])\n",
+    "fs_source.filters.add([f3, f4])\n",
     "\n",
     "\n",
     "mem = MemoryStore()\n",
@@ -442,7 +446,7 @@
     "mem.source.filters.add(f)\n",
     "\n",
     "# attach multiple filters to a MemoryStore\n",
-    "mem.source.filters.update([f1,f2])"
+    "mem.source.filters.add([f1,f2])"
    ]
   },
   {
@@ -457,7 +461,9 @@
   {
    "cell_type": "code",
    "execution_count": 10,
-   "metadata": {},
+   "metadata": {
+    "collapsed": true
+   },
    "outputs": [],
    "source": [
     "from stix2 import Campaign, Identity, Indicator, Malware, Relationship\n",
@@ -719,21 +725,21 @@
  ],
  "metadata": {
   "kernelspec": {
-   "display_name": "Python 3",
+   "display_name": "cti-python-stix2",
    "language": "python",
-   "name": "python3"
+   "name": "cti-python-stix2"
   },
   "language_info": {
    "codemirror_mode": {
     "name": "ipython",
-    "version": 3
+    "version": 2
    },
    "file_extension": ".py",
    "mimetype": "text/x-python",
    "name": "python",
    "nbconvert_exporter": "python",
-   "pygments_lexer": "ipython3",
-   "version": "3.6.3"
+   "pygments_lexer": "ipython2",
+   "version": "2.7.12"
   }
  },
  "nbformat": 4,
diff --git a/stix2/__init__.py b/stix2/__init__.py
index 17f2277..449be68 100644
--- a/stix2/__init__.py
+++ b/stix2/__init__.py
@@ -50,7 +50,7 @@ from .patterns import (AndBooleanExpression, AndObservationExpression,
                        ReferenceObjectPathComponent, RepeatQualifier,
                        StartStopQualifier, StringConstant, TimestampConstant,
                        WithinQualifier)
-from .utils import get_dict, new_version, revoke
+from .utils import new_version, revoke
 from .v20 import *  # This import will always be the latest STIX 2.X version
 from .version import __version__
 
diff --git a/stix2/core.py b/stix2/core.py
index 7de7984..0b222a9 100644
--- a/stix2/core.py
+++ b/stix2/core.py
@@ -9,7 +9,7 @@ import stix2
 from . import exceptions
 from .base import _STIXBase
 from .properties import IDProperty, ListProperty, Property, TypeProperty
-from .utils import get_class_hierarchy_names, get_dict
+from .utils import _get_dict, get_class_hierarchy_names
 
 
 class STIXObjectProperty(Property):
@@ -25,7 +25,7 @@ class STIXObjectProperty(Property):
                for x in get_class_hierarchy_names(value)):
             return value
         try:
-            dictified = get_dict(value)
+            dictified = _get_dict(value)
         except ValueError:
             raise ValueError("This property may only contain a dictionary or object")
         if dictified == {}:
@@ -95,7 +95,7 @@ def parse(data, allow_custom=False, version=None):
 
     """
     # convert STIX object to dict, if not already
-    obj = get_dict(data)
+    obj = _get_dict(data)
 
     # convert dict to full python-stix2 obj
     obj = dict_to_stix2(obj, allow_custom, version)
diff --git a/stix2/datastore/__init__.py b/stix2/datastore/__init__.py
index 4ca9d5f..7fdf515 100644
--- a/stix2/datastore/__init__.py
+++ b/stix2/datastore/__init__.py
@@ -16,7 +16,7 @@ import uuid
 
 from six import with_metaclass
 
-from stix2.datastore.filters import Filter, _assemble_filters
+from stix2.datastore.filters import Filter, FilterSet
 from stix2.utils import deduplicate
 
 
@@ -222,13 +222,13 @@ class DataSource(with_metaclass(ABCMeta)):
 
     Attributes:
         id (str): A unique UUIDv4 to identify this DataSource.
-        filters (set): A collection of filters attached to this DataSource.
+        filters (FilterSet): A collection of filters attached to this DataSource.
 
     """
     def __init__(self):
         super(DataSource, self).__init__()
         self.id = make_id()
-        self.filters = set()
+        self.filters = FilterSet()
 
     @abstractmethod
     def get(self, stix_id):
@@ -379,10 +379,10 @@ class DataSource(with_metaclass(ABCMeta)):
         ids.discard(obj_id)
 
         # Assemble filters
-        filter_list = _assemble_filters(filters)
+        filter_list = FilterSet(filters)
 
         for i in ids:
-            results.extend(self.query(filter_list + [Filter('id', '=', i)]))
+            results.extend(self.query([f for f in filter_list] + [Filter('id', '=', i)]))
 
         return results
 
@@ -427,7 +427,7 @@ class CompositeDataSource(DataSource):
 
         Args:
             stix_id (str): the id of the STIX object to retrieve.
-            _composite_filters (list): a list of filters passed from a
+            _composite_filters (FilterSet): a collection of filters passed from a
                 CompositeDataSource (i.e. if this CompositeDataSource is attached
                 to another parent CompositeDataSource), not user supplied.
 
@@ -439,11 +439,12 @@ class CompositeDataSource(DataSource):
             raise AttributeError('CompositeDataSource has no data sources')
 
         all_data = []
-        all_filters = set()
-        all_filters.update(self.filters)
+        all_filters = FilterSet()
+
+        all_filters.add(self.filters)
 
         if _composite_filters:
-            all_filters.update(_composite_filters)
+            all_filters.add(_composite_filters)
 
         # for every configured Data Source, call its retrieve handler
         for ds in self.data_sources:
@@ -473,7 +474,7 @@ class CompositeDataSource(DataSource):
 
         Args:
             stix_id (str): id of the STIX objects to retrieve.
-            _composite_filters (list): a list of filters passed from a
+            _composite_filters (FilterSet): a collection of filters passed from a
                 CompositeDataSource (i.e. if this CompositeDataSource is
                 attached to a parent CompositeDataSource), not user supplied.
 
@@ -485,12 +486,12 @@ class CompositeDataSource(DataSource):
             raise AttributeError('CompositeDataSource has no data sources')
 
         all_data = []
-        all_filters = set()
+        all_filters = FilterSet()
 
-        all_filters.update(self.filters)
+        all_filters.add(self.filters)
 
         if _composite_filters:
-            all_filters.update(_composite_filters)
+            all_filters.add(_composite_filters)
 
         # retrieve STIX objects from all configured data sources
         for ds in self.data_sources:
@@ -512,7 +513,7 @@ class CompositeDataSource(DataSource):
 
         Args:
             query (list): list of filters to search on.
-            _composite_filters (list): a list of filters passed from a
+            _composite_filters (FilterSet): a collection of filters passed from a
                 CompositeDataSource (i.e. if this CompositeDataSource is
                 attached to a parent CompositeDataSource), not user supplied.
 
@@ -524,17 +525,17 @@ class CompositeDataSource(DataSource):
             raise AttributeError('CompositeDataSource has no data sources')
 
         if not query:
-            # don't mess with the query (i.e. convert to a set, as that's done
+            # don't mess with the query (i.e. deduplicate, as that's done
             # within the specific DataSources that are called)
             query = []
 
         all_data = []
+        all_filters = FilterSet()
 
-        all_filters = set()
-        all_filters.update(self.filters)
+        all_filters.add(self.filters)
 
         if _composite_filters:
-            all_filters.update(_composite_filters)
+            all_filters.add(_composite_filters)
 
         # federate query to all attached data sources,
         # pass composite filters to id
diff --git a/stix2/datastore/filesystem.py b/stix2/datastore/filesystem.py
index a6f31cf..c13b02c 100644
--- a/stix2/datastore/filesystem.py
+++ b/stix2/datastore/filesystem.py
@@ -8,7 +8,7 @@ import os
 
 from stix2.core import Bundle, parse
 from stix2.datastore import DataSink, DataSource, DataStoreMixin
-from stix2.datastore.filters import Filter, apply_common_filters
+from stix2.datastore.filters import Filter, FilterSet, apply_common_filters
 from stix2.utils import deduplicate, get_class_hierarchy_names
 
 
@@ -165,7 +165,7 @@ class FileSystemSource(DataSource):
 
         Args:
             stix_id (str): The STIX ID of the STIX object to be retrieved.
-            _composite_filters (set): set of filters passed from the parent
+            _composite_filters (FilterSet): collection of filters passed from the parent
                 CompositeDataSource, not user supplied
             version (str): Which STIX2 version to use. (e.g. "2.0", "2.1"). If
                 None, use latest version.
@@ -195,7 +195,7 @@ class FileSystemSource(DataSource):
 
         Args:
             stix_id (str): The STIX ID of the STIX objects to be retrieved.
-            _composite_filters (set): set of filters passed from the parent
+            _composite_filters (FilterSet): collection of filters passed from the parent
                 CompositeDataSource, not user supplied
             version (str): Which STIX2 version to use. (e.g. "2.0", "2.1"). If
                 None, use latest version.
@@ -217,7 +217,7 @@ class FileSystemSource(DataSource):
 
         Args:
             query (list): list of filters to search on
-            _composite_filters (set): set of filters passed from the
+            _composite_filters (FilterSet): collection of filters passed from the
                 CompositeDataSource, not user supplied
             version (str): Which STIX2 version to use. (e.g. "2.0", "2.1"). If
                 None, use latest version.
@@ -231,20 +231,13 @@ class FileSystemSource(DataSource):
 
         all_data = []
 
-        if query is None:
-            query = set()
-        else:
-            if not isinstance(query, list):
-                # make sure dont make set from a Filter object,
-                # need to make a set from a list of Filter objects (even if just one Filter)
-                query = [query]
-            query = set(query)
+        query = FilterSet(query)
 
         # combine all query filters
         if self.filters:
-            query.update(self.filters)
+            query.add(self.filters)
         if _composite_filters:
-            query.update(_composite_filters)
+            query.add(_composite_filters)
 
         # extract any filters that are for "type" or "id" , as we can then do
         # filtering before reading in the STIX objects. A STIX 'type' filter
@@ -343,8 +336,8 @@ class FileSystemSource(DataSource):
         search space of a FileSystemStore (or FileSystemSink).
 
         """
-        file_filters = set()
+        file_filters = []
         for filter_ in query:
             if filter_.property == "id" or filter_.property == "type":
-                file_filters.add(filter_)
+                file_filters.append(filter_)
         return file_filters
diff --git a/stix2/datastore/filters.py b/stix2/datastore/filters.py
index 10bbeee..ab94e89 100644
--- a/stix2/datastore/filters.py
+++ b/stix2/datastore/filters.py
@@ -4,6 +4,9 @@ Filters for Python STIX 2.0 DataSources, DataSinks, DataStores
 """
 
 import collections
+from datetime import datetime
+
+from stix2.utils import format_datetime
 
 """Supported filter operations"""
 FILTER_OPS = ['=', '!=', 'in', '>', '<', '>=', '<=']
@@ -44,37 +47,6 @@ def _check_filter_components(prop, op, value):
     return True
 
 
-def _assemble_filters(filters1=None, filters2=None):
-    """Assemble a list of filters.
-
-    This can be used to allow certain functions to work correctly no matter if
-    the user provides a single filter or a list of them.
-
-    Args:
-        filters1 (Filter or list, optional): The single Filter or list of Filters to
-            coerce into a list of Filters.
-        filters2 (Filter or list, optional): The single Filter or list of Filters to
-            append to the list of Filters.
-
-    Returns:
-        List of Filters.
-
-    """
-    if filters1 is None:
-        filter_list = []
-    elif not isinstance(filters1, list):
-        filter_list = [filters1]
-    else:
-        filter_list = filters1
-
-    if isinstance(filters2, list):
-        filter_list.extend(filters2)
-    elif filters2 is not None:
-        filter_list.append(filters2)
-
-    return filter_list
-
-
 class Filter(collections.namedtuple("Filter", ['property', 'op', 'value'])):
     """STIX 2 filters that support the querying functionality of STIX 2
     DataStores and DataSources.
@@ -97,6 +69,10 @@ class Filter(collections.namedtuple("Filter", ['property', 'op', 'value'])):
         if isinstance(value, list):
             value = tuple(value)
 
+        if isinstance(value, datetime):
+            # if value is a datetime obj, convert to str
+            value = format_datetime(value)
+
         _check_filter_components(prop, op, value)
 
         self = super(Filter, cls).__new__(cls, prop, op, value)
@@ -112,6 +88,12 @@ class Filter(collections.namedtuple("Filter", ['property', 'op', 'value'])):
             True if property matches the filter,
             False otherwise.
         """
+        if isinstance(stix_obj_property, datetime):
+            # if a datetime obj, convert to str format before comparison
+            # NOTE: this check seems like it should be done upstream
+            # but will put here for now
+            stix_obj_property = format_datetime(stix_obj_property)
+
         if self.op == "=":
             return stix_obj_property == self.value
         elif self.op == "!=":
@@ -183,19 +165,94 @@ def _check_filter(filter_, stix_obj):
         # Check embedded properties, from e.g. granular_markings or external_references
         sub_property = filter_.property.split(".", 1)[1]
         sub_filter = filter_._replace(property=sub_property)
+
         if isinstance(stix_obj[prop], list):
             for elem in stix_obj[prop]:
                 if _check_filter(sub_filter, elem) is True:
                     return True
             return False
+
         else:
             return _check_filter(sub_filter, stix_obj[prop])
+
     elif isinstance(stix_obj[prop], list):
         # Check each item in list property to see if it matches
         for elem in stix_obj[prop]:
             if filter_._check_property(elem) is True:
                 return True
         return False
+
     else:
         # Check if property matches
         return filter_._check_property(stix_obj[prop])
+
+
+class FilterSet(object):
+    """Internal STIX2 class to facilitate the grouping of Filters
+    into sets. The primary motivation for this class came from the problem
+    that Filters that had a dict as a value could not be added to a Python
+    set as dicts are not hashable. Thus this class provides set functionality
+    but internally stores filters in a list.
+     """
+
+    def __init__(self, filters=None):
+        """
+        Args:
+            filters: see FilterSet.add()
+        """
+        self._filters = []
+        if filters:
+            self.add(filters)
+
+    def __iter__(self):
+        """provide iteration functionality of FilterSet"""
+        for f in self._filters:
+            yield f
+
+    def __len__(self):
+        """provide built-in len() utility of FilterSet"""
+        return len(self._filters)
+
+    def add(self, filters=None):
+        """add a Filter, FilterSet, or list of Filters to the FilterSet
+
+        Operates like set, only adding unique stix2.Filters to the FilterSet
+
+        NOTE: method designed to be very accomodating (i.e. even accepting filters=None)
+        as it allows for blind calls (very useful in DataStore)
+
+        Args:
+            filters: stix2.Filter OR list of stix2.Filter OR stix2.FilterSet
+
+        """
+        if not filters:
+            # so add() can be called blindly, useful for
+            # DataStore/Environment usage of filter operations
+            return
+
+        if not isinstance(filters, (FilterSet, list)):
+            filters = [filters]
+
+        for f in filters:
+            if f not in self._filters:
+                self._filters.append(f)
+
+    def remove(self, filters=None):
+        """remove a Filter, list of Filters, or FilterSet from the FilterSet
+
+        NOTE: method designed to be very accomodating (i.e. even accepting filters=None)
+        as it allows for blind calls (very useful in DataStore)
+
+        Args:
+            filters: stix2.Filter OR list of stix2.Filter or stix2.FilterSet
+        """
+        if not filters:
+            # so remove() can be called blindly, useful for
+            # DataStore/Environemnt usage of filter ops
+            return
+
+        if not isinstance(filters, (FilterSet, list)):
+            filters = [filters]
+
+        for f in filters:
+            self._filters.remove(f)
diff --git a/stix2/datastore/memory.py b/stix2/datastore/memory.py
index 1c4ff6c..c43da8b 100644
--- a/stix2/datastore/memory.py
+++ b/stix2/datastore/memory.py
@@ -18,7 +18,7 @@ import os
 from stix2.base import _STIXBase
 from stix2.core import Bundle, parse
 from stix2.datastore import DataSink, DataSource, DataStoreMixin
-from stix2.datastore.filters import Filter, apply_common_filters
+from stix2.datastore.filters import Filter, FilterSet, apply_common_filters
 
 
 def _add(store, stix_data=None, version=None):
@@ -197,7 +197,7 @@ class MemorySource(DataSource):
 
         Args:
             stix_id (str): The STIX ID of the STIX object to be retrieved.
-            _composite_filters (set): set of filters passed from the parent
+            _composite_filters (FilterSet): collection of filters passed from the parent
                 CompositeDataSource, not user supplied
 
         Returns:
@@ -236,7 +236,7 @@ class MemorySource(DataSource):
 
         Args:
             stix_id (str): The STIX ID of the STIX 2 object to retrieve.
-            _composite_filters (set): set of filters passed from the parent
+            _composite_filters (FilterSet): collection of filters passed from the parent
                 CompositeDataSource, not user supplied
 
         Returns:
@@ -258,7 +258,7 @@ class MemorySource(DataSource):
 
         Args:
             query (list): list of filters to search on
-            _composite_filters (set): set of filters passed from the
+            _composite_filters (FilterSet): collection of filters passed from the
                 CompositeDataSource, not user supplied
 
         Returns:
@@ -269,19 +269,15 @@ class MemorySource(DataSource):
 
         """
         if query is None:
-            query = set()
+            query = FilterSet()
         else:
-            if not isinstance(query, list):
-                # make sure don't make set from a Filter object,
-                # need to make a set from a list of Filter objects (even if just one Filter)
-                query = [query]
-            query = set(query)
+            query = FilterSet(query)
 
         # combine all query filters
         if self.filters:
-            query.update(self.filters)
+            query.add(self.filters)
         if _composite_filters:
-            query.update(_composite_filters)
+            query.add(_composite_filters)
 
         # Apply STIX common property filters.
         all_data = list(apply_common_filters(self._data.values(), query))
diff --git a/stix2/datastore/taxii.py b/stix2/datastore/taxii.py
index 0a58763..faa2669 100644
--- a/stix2/datastore/taxii.py
+++ b/stix2/datastore/taxii.py
@@ -6,7 +6,7 @@ from requests.exceptions import HTTPError
 from stix2.base import _STIXBase
 from stix2.core import Bundle, parse
 from stix2.datastore import DataSink, DataSource, DataStoreMixin
-from stix2.datastore.filters import Filter, apply_common_filters
+from stix2.datastore.filters import Filter, FilterSet, apply_common_filters
 from stix2.utils import deduplicate
 
 TAXII_FILTERS = ['added_after', 'id', 'type', 'version']
@@ -120,7 +120,7 @@ class TAXIICollectionSource(DataSource):
 
         Args:
             stix_id (str): The STIX ID of the STIX object to be retrieved.
-            _composite_filters (set): set of filters passed from the parent
+            _composite_filters (FilterSet): collection of filters passed from the parent
                 CompositeDataSource, not user supplied
             version (str): Which STIX2 version to use. (e.g. "2.0", "2.1"). If
                 None, use latest version.
@@ -132,11 +132,12 @@ class TAXIICollectionSource(DataSource):
 
         """
         # combine all query filters
-        query = set()
+        query = FilterSet()
+
         if self.filters:
-            query.update(self.filters)
+            query.add(self.filters)
         if _composite_filters:
-            query.update(_composite_filters)
+            query.add(_composite_filters)
 
         # dont extract TAXII filters from query (to send to TAXII endpoint)
         # as directly retrieveing a STIX object by ID
@@ -164,7 +165,7 @@ class TAXIICollectionSource(DataSource):
 
         Args:
             stix_id (str): The STIX ID of the STIX objects to be retrieved.
-            _composite_filters (set): set of filters passed from the parent
+            _composite_filters (FilterSet): collection of filters passed from the parent
                 CompositeDataSource, not user supplied
             version (str): Which STIX2 version to use. (e.g. "2.0", "2.1"). If
                 None, use latest version.
@@ -198,7 +199,7 @@ class TAXIICollectionSource(DataSource):
 
         Args:
             query (list): list of filters to search on
-            _composite_filters (set): set of filters passed from the
+            _composite_filters (FilterSet): collection of filters passed from the
                 CompositeDataSource, not user supplied
             version (str): Which STIX2 version to use. (e.g. "2.0", "2.1"). If
                 None, use latest version.
@@ -209,20 +210,13 @@ class TAXIICollectionSource(DataSource):
                 parsed into python STIX objects and then returned.
 
         """
-        if query is None:
-            query = set()
-        else:
-            if not isinstance(query, list):
-                # make sure dont make set from a Filter object,
-                # need to make a set from a list of Filter objects (even if just one Filter)
-                query = [query]
-            query = set(query)
+        query = FilterSet(query)
 
         # combine all query filters
         if self.filters:
-            query.update(self.filters)
+            query.add(self.filters)
         if _composite_filters:
-            query.update(_composite_filters)
+            query.add(_composite_filters)
 
         # parse taxii query params (that can be applied remotely)
         taxii_filters = self._parse_taxii_filters(query)
@@ -268,17 +262,16 @@ class TAXIICollectionSource(DataSource):
 
 
         Args:
-            query (set): set of filters to extract which ones are TAXII
+            query (list): list of filters to extract which ones are TAXII
                 specific.
 
-        Returns:
-            taxii_filters (set): set of the TAXII filters
+        Returns: a list of the TAXII filters
 
         """
-        taxii_filters = set()
+        taxii_filters = []
 
         for filter_ in query:
             if filter_.property in TAXII_FILTERS:
-                taxii_filters.add(filter_)
+                taxii_filters.append(filter_)
 
         return taxii_filters
diff --git a/stix2/environment.py b/stix2/environment.py
index a456e95..cc589ae 100644
--- a/stix2/environment.py
+++ b/stix2/environment.py
@@ -158,7 +158,7 @@ class Environment(DataStoreMixin):
     set_default_object_marking_refs.__doc__ = ObjectFactory.set_default_object_marking_refs.__doc__
 
     def add_filters(self, *args, **kwargs):
-        return self.source.filters.update(*args, **kwargs)
+        return self.source.filters.add(*args, **kwargs)
 
     def add_filter(self, *args, **kwargs):
         return self.source.filters.add(*args, **kwargs)
diff --git a/stix2/properties.py b/stix2/properties.py
index 41841b6..39d383a 100644
--- a/stix2/properties.py
+++ b/stix2/properties.py
@@ -12,7 +12,7 @@ from stix2patterns.validator import run_validator
 
 from .base import _STIXBase
 from .exceptions import DictionaryKeyError
-from .utils import get_dict, parse_into_datetime
+from .utils import _get_dict, parse_into_datetime
 
 
 class Property(object):
@@ -234,7 +234,7 @@ class DictionaryProperty(Property):
 
     def clean(self, value):
         try:
-            dictified = get_dict(value)
+            dictified = _get_dict(value)
         except ValueError:
             raise ValueError("The dictionary property must contain a dictionary")
         if dictified == {}:
diff --git a/stix2/test/test_datastore.py b/stix2/test/test_datastore.py
index 8f40401..1c7fa43 100644
--- a/stix2/test/test_datastore.py
+++ b/stix2/test/test_datastore.py
@@ -2,10 +2,11 @@ import pytest
 from taxii2client import Collection
 
 from stix2 import Filter, MemorySink, MemorySource
+from stix2.core import parse
 from stix2.datastore import (CompositeDataSource, DataSink, DataSource,
                              make_id, taxii)
-from stix2.datastore.filters import _assemble_filters, apply_common_filters
-from stix2.utils import deduplicate
+from stix2.datastore.filters import apply_common_filters
+from stix2.utils import STIXdatetime, deduplicate, parse_into_datetime
 
 COLLECTION_URL = 'https://example.com/api1/collections/91a7b528-80eb-42ed-a74d-c6fbd5a26116/'
 
@@ -20,6 +21,108 @@ def collection():
     return Collection(COLLECTION_URL, MockTAXIIClient())
 
 
+stix_objs = [
+    {
+        "created": "2017-01-27T13:49:53.997Z",
+        "description": "\n\nTITLE:\n\tPoison Ivy",
+        "id": "malware--fdd60b30-b67c-11e3-b0b9-f01faf20d111",
+        "labels": [
+            "remote-access-trojan"
+        ],
+        "modified": "2017-01-27T13:49:53.997Z",
+        "name": "Poison Ivy",
+        "type": "malware"
+    },
+    {
+        "created": "2014-05-08T09:00:00.000Z",
+        "id": "indicator--a932fcc6-e032-176c-126f-cb970a5a1ade",
+        "labels": [
+            "file-hash-watchlist"
+        ],
+        "modified": "2014-05-08T09:00:00.000Z",
+        "name": "File hash for Poison Ivy variant",
+        "pattern": "[file:hashes.'SHA-256' = 'ef537f25c895bfa782526529a9b63d97aa631564d5d789c2b765448c8635fb6c']",
+        "type": "indicator",
+        "valid_from": "2014-05-08T09:00:00.000000Z"
+    },
+    {
+        "created": "2014-05-08T09:00:00.000Z",
+        "granular_markings": [
+            {
+                "marking_ref": "marking-definition--5e57c739-391a-4eb3-b6be-7d15ca92d5ed",
+                "selectors": [
+                    "relationship_type"
+                ]
+            }
+        ],
+        "id": "relationship--2f9a9aa9-108a-4333-83e2-4fb25add0463",
+        "modified": "2014-05-08T09:00:00.000Z",
+        "object_marking_refs": [
+            "marking-definition--613f2e26-407d-48c7-9eca-b8e91df99dc9"
+        ],
+        "relationship_type": "indicates",
+        "revoked": True,
+        "source_ref": "indicator--a932fcc6-e032-176c-126f-cb970a5a1ade",
+        "target_ref": "malware--fdd60b30-b67c-11e3-b0b9-f01faf20d111",
+        "type": "relationship"
+    },
+    {
+        "id": "vulnerability--ee916c28-c7a4-4d0d-ad56-a8d357f89fef",
+        "created": "2016-02-14T00:00:00.000Z",
+        "created_by_ref": "identity--00000000-0000-0000-0000-b8e91df99dc9",
+        "modified": "2016-02-14T00:00:00.000Z",
+        "type": "vulnerability",
+        "name": "CVE-2014-0160",
+        "description": "The (1) TLS...",
+        "external_references": [
+            {
+                "source_name": "cve",
+                "external_id": "CVE-2014-0160"
+            }
+        ],
+        "labels": ["heartbleed", "has-logo"]
+    },
+    {
+        "type": "observed-data",
+        "id": "observed-data--b67d30ff-02ac-498a-92f9-32f845f448cf",
+        "created_by_ref": "identity--f431f809-377b-45e0-aa1c-6a4751cae5ff",
+        "created": "2016-04-06T19:58:16.000Z",
+        "modified": "2016-04-06T19:58:16.000Z",
+        "first_observed": "2015-12-21T19:00:00Z",
+        "last_observed": "2015-12-21T19:00:00Z",
+        "number_observed": 1,
+        "objects": {
+            "0": {
+                "type": "file",
+                "name": "HAL 9000.exe"
+            }
+        }
+
+    }
+]
+
+# same as above objects but converted to real Python STIX2 objects
+# to test filters against true Python STIX2 objects
+real_stix_objs = [parse(stix_obj) for stix_obj in stix_objs]
+
+filters = [
+    Filter("type", "!=", "relationship"),
+    Filter("id", "=", "relationship--2f9a9aa9-108a-4333-83e2-4fb25add0463"),
+    Filter("labels", "in", "remote-access-trojan"),
+    Filter("created", ">", "2015-01-01T01:00:00.000Z"),
+    Filter("revoked", "=", True),
+    Filter("revoked", "!=", True),
+    Filter("object_marking_refs", "=", "marking-definition--613f2e26-407d-48c7-9eca-b8e91df99dc9"),
+    Filter("granular_markings.selectors", "in", "relationship_type"),
+    Filter("granular_markings.marking_ref", "=", "marking-definition--5e57c739-391a-4eb3-b6be-7d15ca92d5ed"),
+    Filter("external_references.external_id", "in", "CVE-2014-0160,CVE-2017-6608"),
+    Filter("created_by_ref", "=", "identity--00000000-0000-0000-0000-b8e91df99dc9"),
+    Filter("object_marking_refs", "=", "marking-definition--613f2e26-0000-0000-0000-b8e91df99dc9"),
+    Filter("granular_markings.selectors", "in", "description"),
+    Filter("external_references.source_name", "=", "CVE"),
+    Filter("objects", "=", {"0": {"type": "file", "name": "HAL 9000.exe"}})
+]
+
 IND1 = {
     "created": "2017-01-27T13:49:53.935Z",
     "id": "indicator--d81f86b9-975b-bc0b-775e-810c5ad45a4f",
@@ -120,6 +223,9 @@ IND8 = {
 STIX_OBJS2 = [IND6, IND7, IND8]
 STIX_OBJS1 = [IND1, IND2, IND3, IND4, IND5]
 
+REAL_STIX_OBJS2 = [parse(IND6), parse(IND7), parse(IND8)]
+REAL_STIX_OBJS1 = [parse(IND1), parse(IND2), parse(IND3), parse(IND4), parse(IND5)]
+
 
 def test_ds_abstract_class_smoke():
     with pytest.raises(TypeError):
@@ -148,12 +254,12 @@ def test_parse_taxii_filters():
         Filter("created_by_ref", "=", "Bane"),
     ]
 
-    taxii_filters_expected = set([
+    taxii_filters_expected = [
         Filter("added_after", "=", "2016-02-01T00:00:01.000Z"),
         Filter("id", "=", "taxii stix object ID"),
         Filter("type", "=", "taxii stix object ID"),
         Filter("version", "=", "first")
-    ])
+    ]
 
     ds = taxii.TAXIICollectionSource(collection)
 
@@ -177,7 +283,7 @@ def test_add_get_remove_filter():
     ds.filters.add(valid_filters[0])
     assert len(ds.filters) == 1
 
-    # Addin the same filter again will have no effect since `filters` uses a set
+    # Addin the same filter again will have no effect since `filters` acts like a set
     ds.filters.add(valid_filters[0])
     assert len(ds.filters) == 1
 
@@ -186,14 +292,14 @@ def test_add_get_remove_filter():
     ds.filters.add(valid_filters[2])
     assert len(ds.filters) == 3
 
-    assert set(valid_filters) == ds.filters
+    assert valid_filters == [f for f in ds.filters]
 
     # remove
     ds.filters.remove(valid_filters[0])
 
     assert len(ds.filters) == 2
 
-    ds.filters.update(valid_filters)
+    ds.filters.add(valid_filters)
 
 
 def test_filter_ops_check():
@@ -236,153 +342,199 @@ def test_filter_type_underscore_check():
     assert "Filter for property 'type' cannot have its value 'oh_underscore'" in str(excinfo.value)
 
 
-def test_apply_common_filters():
-    stix_objs = [
-        {
-            "created": "2017-01-27T13:49:53.997Z",
-            "description": "\n\nTITLE:\n\tPoison Ivy",
-            "id": "malware--fdd60b30-b67c-11e3-b0b9-f01faf20d111",
-            "labels": [
-                "remote-access-trojan"
-            ],
-            "modified": "2017-01-27T13:49:53.997Z",
-            "name": "Poison Ivy",
-            "type": "malware"
-        },
-        {
-            "created": "2014-05-08T09:00:00.000Z",
-            "id": "indicator--a932fcc6-e032-176c-126f-cb970a5a1ade",
-            "labels": [
-                "file-hash-watchlist"
-            ],
-            "modified": "2014-05-08T09:00:00.000Z",
-            "name": "File hash for Poison Ivy variant",
-            "pattern": "[file:hashes.'SHA-256' = 'ef537f25c895bfa782526529a9b63d97aa631564d5d789c2b765448c8635fb6c']",
-            "type": "indicator",
-            "valid_from": "2014-05-08T09:00:00.000000Z"
-        },
-        {
-            "created": "2014-05-08T09:00:00.000Z",
-            "granular_markings": [
-                {
-                    "marking_ref": "marking-definition--5e57c739-391a-4eb3-b6be-7d15ca92d5ed",
-                    "selectors": [
-                        "relationship_type"
-                    ]
-                }
-            ],
-            "id": "relationship--2f9a9aa9-108a-4333-83e2-4fb25add0463",
-            "modified": "2014-05-08T09:00:00.000Z",
-            "object_marking_refs": [
-                "marking-definition--613f2e26-407d-48c7-9eca-b8e91df99dc9"
-            ],
-            "relationship_type": "indicates",
-            "revoked": True,
-            "source_ref": "indicator--a932fcc6-e032-176c-126f-cb970a5a1ade",
-            "target_ref": "malware--fdd60b30-b67c-11e3-b0b9-f01faf20d111",
-            "type": "relationship"
-        },
-        {
-            "id": "vulnerability--ee916c28-c7a4-4d0d-ad56-a8d357f89fef",
-            "created": "2016-02-14T00:00:00.000Z",
-            "created_by_ref": "identity--00000000-0000-0000-0000-b8e91df99dc9",
-            "modified": "2016-02-14T00:00:00.000Z",
-            "type": "vulnerability",
-            "name": "CVE-2014-0160",
-            "description": "The (1) TLS...",
-            "external_references": [
-                {
-                    "source_name": "cve",
-                    "external_id": "CVE-2014-0160"
-                }
-            ],
-            "labels": ["heartbleed", "has-logo"]
-        }
-    ]
-
-    filters = [
-        Filter("type", "!=", "relationship"),
-        Filter("id", "=", "relationship--2f9a9aa9-108a-4333-83e2-4fb25add0463"),
-        Filter("labels", "in", "remote-access-trojan"),
-        Filter("created", ">", "2015-01-01T01:00:00.000Z"),
-        Filter("revoked", "=", True),
-        Filter("revoked", "!=", True),
-        Filter("object_marking_refs", "=", "marking-definition--613f2e26-407d-48c7-9eca-b8e91df99dc9"),
-        Filter("granular_markings.selectors", "in", "relationship_type"),
-        Filter("granular_markings.marking_ref", "=", "marking-definition--5e57c739-391a-4eb3-b6be-7d15ca92d5ed"),
-        Filter("external_references.external_id", "in", "CVE-2014-0160,CVE-2017-6608"),
-        Filter("created_by_ref", "=", "identity--00000000-0000-0000-0000-b8e91df99dc9"),
-        Filter("object_marking_refs", "=", "marking-definition--613f2e26-0000-0000-0000-b8e91df99dc9"),
-        Filter("granular_markings.selectors", "in", "description"),
-        Filter("external_references.source_name", "=", "CVE"),
-    ]
-
+def test_apply_common_filters0():
     # "Return any object whose type is not relationship"
     resp = list(apply_common_filters(stix_objs, [filters[0]]))
     ids = [r['id'] for r in resp]
     assert stix_objs[0]['id'] in ids
     assert stix_objs[1]['id'] in ids
     assert stix_objs[3]['id'] in ids
-    assert len(ids) == 3
+    assert len(ids) == 4
 
+    resp = list(apply_common_filters(real_stix_objs, [filters[0]]))
+    ids = [r.id for r in resp]
+    assert real_stix_objs[0].id in ids
+    assert real_stix_objs[1].id in ids
+    assert real_stix_objs[3].id in ids
+    assert len(ids) == 4
+
+
+def test_apply_common_filters1():
     # "Return any object that matched id relationship--2f9a9aa9-108a-4333-83e2-4fb25add0463"
     resp = list(apply_common_filters(stix_objs, [filters[1]]))
     assert resp[0]['id'] == stix_objs[2]['id']
     assert len(resp) == 1
 
+    resp = list(apply_common_filters(real_stix_objs, [filters[1]]))
+    assert resp[0].id == real_stix_objs[2].id
+    assert len(resp) == 1
+
+
+def test_apply_common_filters2():
     # "Return any object that contains remote-access-trojan in labels"
     resp = list(apply_common_filters(stix_objs, [filters[2]]))
     assert resp[0]['id'] == stix_objs[0]['id']
     assert len(resp) == 1
 
+    resp = list(apply_common_filters(real_stix_objs, [filters[2]]))
+    assert resp[0].id == real_stix_objs[0].id
+    assert len(resp) == 1
+
+
+def test_apply_common_filters3():
     # "Return any object created after 2015-01-01T01:00:00.000Z"
     resp = list(apply_common_filters(stix_objs, [filters[3]]))
     assert resp[0]['id'] == stix_objs[0]['id']
-    assert len(resp) == 2
+    assert len(resp) == 3
 
+    resp = list(apply_common_filters(real_stix_objs, [filters[3]]))
+    assert resp[0].id == real_stix_objs[0].id
+    assert len(resp) == 3
+
+
+def test_apply_common_filters4():
     # "Return any revoked object"
     resp = list(apply_common_filters(stix_objs, [filters[4]]))
     assert resp[0]['id'] == stix_objs[2]['id']
     assert len(resp) == 1
 
+    resp = list(apply_common_filters(real_stix_objs, [filters[4]]))
+    assert resp[0].id == real_stix_objs[2].id
+    assert len(resp) == 1
+
+
+def test_apply_common_filters5():
     # "Return any object whose not revoked"
     # Note that if 'revoked' property is not present in object.
     # Currently we can't use such an expression to filter for... :(
     resp = list(apply_common_filters(stix_objs, [filters[5]]))
     assert len(resp) == 0
 
+    resp = list(apply_common_filters(real_stix_objs, [filters[5]]))
+    assert len(resp) == 0
+
+
+def test_apply_common_filters6():
     # "Return any object that matches marking-definition--613f2e26-407d-48c7-9eca-b8e91df99dc9 in object_marking_refs"
     resp = list(apply_common_filters(stix_objs, [filters[6]]))
     assert resp[0]['id'] == stix_objs[2]['id']
     assert len(resp) == 1
 
+    resp = list(apply_common_filters(real_stix_objs, [filters[6]]))
+    assert resp[0].id == real_stix_objs[2].id
+    assert len(resp) == 1
+
+
+def test_apply_common_filters7():
     # "Return any object that contains relationship_type in their selectors AND
     # also has marking-definition--5e57c739-391a-4eb3-b6be-7d15ca92d5ed in marking_ref"
     resp = list(apply_common_filters(stix_objs, [filters[7], filters[8]]))
     assert resp[0]['id'] == stix_objs[2]['id']
     assert len(resp) == 1
 
+    resp = list(apply_common_filters(real_stix_objs, [filters[7], filters[8]]))
+    assert resp[0].id == real_stix_objs[2].id
+    assert len(resp) == 1
+
+
+def test_apply_common_filters8():
     # "Return any object that contains CVE-2014-0160,CVE-2017-6608 in their external_id"
     resp = list(apply_common_filters(stix_objs, [filters[9]]))
     assert resp[0]['id'] == stix_objs[3]['id']
     assert len(resp) == 1
 
+    resp = list(apply_common_filters(real_stix_objs, [filters[9]]))
+    assert resp[0].id == real_stix_objs[3].id
+    assert len(resp) == 1
+
+
+def test_apply_common_filters9():
     # "Return any object that matches created_by_ref identity--00000000-0000-0000-0000-b8e91df99dc9"
     resp = list(apply_common_filters(stix_objs, [filters[10]]))
     assert len(resp) == 1
 
+    resp = list(apply_common_filters(real_stix_objs, [filters[10]]))
+    assert len(resp) == 1
+
+
+def test_apply_common_filters10():
     # "Return any object that matches marking-definition--613f2e26-0000-0000-0000-b8e91df99dc9 in object_marking_refs" (None)
     resp = list(apply_common_filters(stix_objs, [filters[11]]))
     assert len(resp) == 0
 
+    resp = list(apply_common_filters(real_stix_objs, [filters[11]]))
+    assert len(resp) == 0
+
+
+def test_apply_common_filters11():
     # "Return any object that contains description in its selectors" (None)
     resp = list(apply_common_filters(stix_objs, [filters[12]]))
     assert len(resp) == 0
 
-    # "Return any object that object that matches CVE in source_name" (None, case sensitive)
+    resp = list(apply_common_filters(real_stix_objs, [filters[12]]))
+    assert len(resp) == 0
+
+
+def test_apply_common_filters12():
+    # "Return any object that matches CVE in source_name" (None, case sensitive)
     resp = list(apply_common_filters(stix_objs, [filters[13]]))
     assert len(resp) == 0
 
+    resp = list(apply_common_filters(real_stix_objs, [filters[13]]))
+    assert len(resp) == 0
+
+
+def test_apply_common_filters13():
+    # Return any object that matches file object in "objects"
+    resp = list(apply_common_filters(stix_objs, [filters[14]]))
+    assert resp[0]["id"] == stix_objs[4]["id"]
+    assert len(resp) == 1
+    # important additional check to make sure original File dict was
+    # not converted to File object. (this was a deep bug found)
+    assert isinstance(resp[0]["objects"]["0"], dict)
+
+    resp = list(apply_common_filters(real_stix_objs, [filters[14]]))
+    assert resp[0].id == real_stix_objs[4].id
+    assert len(resp) == 1
+
+
+def test_datetime_filter_behavior():
+    """if a filter is initialized with its value being a datetime object
+    OR the STIX object property being filtered on is a datetime object, all
+    resulting comparisons executed are done on the string representations
+    of the datetime objects, as the Filter functionality will convert
+    all datetime objects to there string forms using format_datetim()
+
+    This test makes sure all datetime comparisons are carried out correctly
+    """
+    filter_with_dt_obj = Filter("created", "=", parse_into_datetime("2016-02-14T00:00:00.000Z", "millisecond"))
+    filter_with_str = Filter("created", "=", "2016-02-14T00:00:00.000Z")
+
+    # check that filter value is converted from datetime to str
+    assert isinstance(filter_with_dt_obj.value, str)
+
+    # compare datetime string to filter w/ datetime obj
+    resp = list(apply_common_filters(stix_objs, [filter_with_dt_obj]))
+    assert len(resp) == 1
+    assert resp[0]["id"] == "vulnerability--ee916c28-c7a4-4d0d-ad56-a8d357f89fef"
+
+    # compare datetime obj to filter w/ datetime obj
+    resp = list(apply_common_filters(real_stix_objs, [filter_with_dt_obj]))
+    assert len(resp) == 1
+    assert resp[0]["id"] == "vulnerability--ee916c28-c7a4-4d0d-ad56-a8d357f89fef"
+    assert isinstance(resp[0].created, STIXdatetime)  # make sure original object not altered
+
+    # compare datetime string to filter w/ str
+    resp = list(apply_common_filters(stix_objs, [filter_with_str]))
+    assert len(resp) == 1
+    assert resp[0]["id"] == "vulnerability--ee916c28-c7a4-4d0d-ad56-a8d357f89fef"
+
+    # compare datetime obj to filter w/ str
+    resp = list(apply_common_filters(real_stix_objs, [filter_with_str]))
+    assert len(resp) == 1
+    assert resp[0]["id"] == "vulnerability--ee916c28-c7a4-4d0d-ad56-a8d357f89fef"
+    assert isinstance(resp[0].created, STIXdatetime)  # make sure original object not altered
+
 
 def test_filters0():
     # "Return any object modified before 2017-01-28T13:49:53.935Z"
@@ -390,6 +542,10 @@ def test_filters0():
     assert resp[0]['id'] == STIX_OBJS2[1]['id']
     assert len(resp) == 2
 
+    resp = list(apply_common_filters(REAL_STIX_OBJS2, [Filter("modified", "<", parse_into_datetime("2017-01-28T13:49:53.935Z"))]))
+    assert resp[0].id == REAL_STIX_OBJS2[1].id
+    assert len(resp) == 2
+
 
 def test_filters1():
     # "Return any object modified after 2017-01-28T13:49:53.935Z"
@@ -397,6 +553,10 @@ def test_filters1():
     assert resp[0]['id'] == STIX_OBJS2[0]['id']
     assert len(resp) == 1
 
+    resp = list(apply_common_filters(REAL_STIX_OBJS2, [Filter("modified", ">", parse_into_datetime("2017-01-28T13:49:53.935Z"))]))
+    assert resp[0].id == REAL_STIX_OBJS2[0].id
+    assert len(resp) == 1
+
 
 def test_filters2():
     # "Return any object modified after or on 2017-01-28T13:49:53.935Z"
@@ -404,6 +564,10 @@ def test_filters2():
     assert resp[0]['id'] == STIX_OBJS2[0]['id']
     assert len(resp) == 3
 
+    resp = list(apply_common_filters(REAL_STIX_OBJS2, [Filter("modified", ">=", parse_into_datetime("2017-01-27T13:49:53.935Z"))]))
+    assert resp[0].id == REAL_STIX_OBJS2[0].id
+    assert len(resp) == 3
+
 
 def test_filters3():
     # "Return any object modified before or on 2017-01-28T13:49:53.935Z"
@@ -411,6 +575,12 @@ def test_filters3():
     assert resp[0]['id'] == STIX_OBJS2[1]['id']
     assert len(resp) == 2
 
+    # "Return any object modified before or on 2017-01-28T13:49:53.935Z"
+    fv = Filter("modified", "<=", parse_into_datetime("2017-01-27T13:49:53.935Z"))
+    resp = list(apply_common_filters(REAL_STIX_OBJS2, [fv]))
+    assert resp[0].id == REAL_STIX_OBJS2[1].id
+    assert len(resp) == 2
+
 
 def test_filters4():
     # Assert invalid Filter cannot be created
@@ -426,6 +596,10 @@ def test_filters5():
     assert resp[0]['id'] == STIX_OBJS2[0]['id']
     assert len(resp) == 1
 
+    resp = list(apply_common_filters(REAL_STIX_OBJS2, [Filter("id", "!=", "indicator--d81f86b8-975b-bc0b-775e-810c5ad45a4f")]))
+    assert resp[0].id == REAL_STIX_OBJS2[0].id
+    assert len(resp) == 1
+
 
 def test_filters6():
     # Test filtering on non-common property
@@ -433,10 +607,14 @@ def test_filters6():
     assert resp[0]['id'] == STIX_OBJS2[0]['id']
     assert len(resp) == 3
 
+    resp = list(apply_common_filters(REAL_STIX_OBJS2, [Filter("name", "=", "Malicious site hosting downloader")]))
+    assert resp[0].id == REAL_STIX_OBJS2[0].id
+    assert len(resp) == 3
+
 
 def test_filters7():
     # Test filtering on embedded property
-    stix_objects = list(STIX_OBJS2) + [{
+    obsvd_data_obj = {
         "type": "observed-data",
         "id": "observed-data--b67d30ff-02ac-498a-92f9-32f845f448cf",
         "created_by_ref": "identity--f431f809-377b-45e0-aa1c-6a4751cae5ff",
@@ -467,19 +645,18 @@ def test_filters7():
                 }
             }
         }
-    }]
+    }
+
+    stix_objects = list(STIX_OBJS2) + [obsvd_data_obj]
+    real_stix_objects = list(REAL_STIX_OBJS2) + [parse(obsvd_data_obj)]
+
     resp = list(apply_common_filters(stix_objects, [Filter("objects.0.extensions.pdf-ext.version", ">", "1.2")]))
     assert resp[0]['id'] == stix_objects[3]['id']
     assert len(resp) == 1
 
-
-def test_assemble_filters():
-    filter1 = Filter("name", "=", "Malicious site hosting downloader")
-    filter2 = Filter("modified", ">", "2017-01-28T13:49:53.935Z")
-    result = _assemble_filters(filter1, filter2)
-    assert len(result) == 2
-    assert result[0].property == 'name'
-    assert result[1].property == 'modified'
+    resp = list(apply_common_filters(real_stix_objects, [Filter("objects.0.extensions.pdf-ext.version", ">", "1.2")]))
+    assert resp[0].id == real_stix_objects[3].id
+    assert len(resp) == 1
 
 
 def test_deduplicate():
@@ -557,7 +734,7 @@ def test_composite_datasource_operations():
         Filter("valid_from", "=", "2017-01-27T13:49:53.935382Z")
     ]
 
-    cds1.filters.update(query2)
+    cds1.filters.add(query2)
 
     results = cds1.query(query1)
 
diff --git a/stix2/test/test_utils.py b/stix2/test/test_utils.py
index cbe5b0f..84b2476 100644
--- a/stix2/test/test_utils.py
+++ b/stix2/test/test_utils.py
@@ -62,7 +62,7 @@ def test_parse_datetime_invalid(ts):
     [("a", 1,)],
 ])
 def test_get_dict(data):
-    assert stix2.utils.get_dict(data)
+    assert stix2.utils._get_dict(data)
 
 
 @pytest.mark.parametrize('data', [
@@ -73,7 +73,7 @@ def test_get_dict(data):
 ])
 def test_get_dict_invalid(data):
     with pytest.raises(ValueError):
-        stix2.utils.get_dict(data)
+        stix2.utils._get_dict(data)
 
 
 @pytest.mark.parametrize('stix_id, typ', [
diff --git a/stix2/utils.py b/stix2/utils.py
index e693d08..619652a 100644
--- a/stix2/utils.py
+++ b/stix2/utils.py
@@ -142,7 +142,7 @@ def parse_into_datetime(value, precision=None):
     return STIXdatetime(ts, precision=precision)
 
 
-def get_dict(data):
+def _get_dict(data):
     """Return data as a dictionary.
 
     Input can be a dictionary, string, or file-like object.
diff --git a/stix2/v20/common.py b/stix2/v20/common.py
index e915df6..0bba3b1 100644
--- a/stix2/v20/common.py
+++ b/stix2/v20/common.py
@@ -7,7 +7,7 @@ from ..markings import _MarkingsMixin
 from ..properties import (HashesProperty, IDProperty, ListProperty, Property,
                           ReferenceProperty, SelectorProperty, StringProperty,
                           TimestampProperty, TypeProperty)
-from ..utils import NOW, get_dict
+from ..utils import NOW, _get_dict
 
 
 class ExternalReference(_STIXBase):
@@ -125,7 +125,7 @@ class MarkingDefinition(_STIXBase, _MarkingsMixin):
                 raise ValueError("definition_type must be a valid marking type")
 
             if not isinstance(kwargs['definition'], marking_type):
-                defn = get_dict(kwargs['definition'])
+                defn = _get_dict(kwargs['definition'])
                 kwargs['definition'] = marking_type(**defn)
 
         super(MarkingDefinition, self).__init__(**kwargs)
diff --git a/stix2/v20/observables.py b/stix2/v20/observables.py
index 773611e..6c65e8e 100644
--- a/stix2/v20/observables.py
+++ b/stix2/v20/observables.py
@@ -6,6 +6,7 @@ Observable and do not have a ``_type`` attribute.
 """
 
 from collections import OrderedDict
+import copy
 import re
 
 from ..base import _Extension, _Observable, _STIXBase
@@ -16,7 +17,7 @@ from ..properties import (BinaryProperty, BooleanProperty, DictionaryProperty,
                           HashesProperty, HexProperty, IntegerProperty,
                           ListProperty, ObjectReferenceProperty, Property,
                           StringProperty, TimestampProperty, TypeProperty)
-from ..utils import TYPE_REGEX, get_dict
+from ..utils import TYPE_REGEX, _get_dict
 
 
 class ObservableProperty(Property):
@@ -25,7 +26,11 @@ class ObservableProperty(Property):
 
     def clean(self, value):
         try:
-            dictified = get_dict(value)
+            dictified = _get_dict(value)
+            # get deep copy since we are going modify the dict and might
+            # modify the original dict as _get_dict() does not return new
+            # dict when passed a dict
+            dictified = copy.deepcopy(dictified)
         except ValueError:
             raise ValueError("The observable property must contain a dictionary")
         if dictified == {}:
@@ -50,7 +55,11 @@ class ExtensionsProperty(DictionaryProperty):
 
     def clean(self, value):
         try:
-            dictified = get_dict(value)
+            dictified = _get_dict(value)
+            # get deep copy since we are going modify the dict and might
+            # modify the original dict as _get_dict() does not return new
+            # dict when passed a dict
+            dictified = copy.deepcopy(dictified)
         except ValueError:
             raise ValueError("The extensions property must contain a dictionary")
         if dictified == {}:
@@ -916,7 +925,12 @@ def parse_observable(data, _valid_refs=None, allow_custom=False):
         An instantiated Python STIX Cyber Observable object.
     """
 
-    obj = get_dict(data)
+    obj = _get_dict(data)
+    # get deep copy since we are going modify the dict and might
+    # modify the original dict as _get_dict() does not return new
+    # dict when passed a dict
+    obj = copy.deepcopy(obj)
+
     obj['_valid_refs'] = _valid_refs or []
 
     if 'type' not in obj:
diff --git a/stix2/workbench.py b/stix2/workbench.py
index b47968e..3697c63 100644
--- a/stix2/workbench.py
+++ b/stix2/workbench.py
@@ -48,7 +48,7 @@ from . import (AlternateDataStream, ArchiveExt, Artifact, AutonomousSystem,  # n
                WindowsPEOptionalHeaderType, WindowsPESection,
                WindowsProcessExt, WindowsRegistryKey, WindowsRegistryValueType,
                WindowsServiceExt, X509Certificate, X509V3ExtenstionsType)
-from .datastore.filters import _assemble_filters
+from .datastore.filters import FilterSet
 
 # Use an implicit MemoryStore
 _environ = Environment(store=MemoryStore())
@@ -156,7 +156,8 @@ def attack_patterns(filters=None):
             the query.
 
     """
-    filter_list = _assemble_filters(filters, [Filter('type', '=', 'attack-pattern')])
+    filter_list = FilterSet(filters)
+    filter_list.add(Filter('type', '=', 'attack-pattern'))
     return query(filter_list)
 
 
@@ -168,7 +169,8 @@ def campaigns(filters=None):
             the query.
 
     """
-    filter_list = _assemble_filters(filters, [Filter('type', '=', 'campaign')])
+    filter_list = FilterSet(filters)
+    filter_list.add(Filter('type', '=', 'campaign'))
     return query(filter_list)
 
 
@@ -180,7 +182,8 @@ def courses_of_action(filters=None):
             the query.
 
     """
-    filter_list = _assemble_filters(filters, [Filter('type', '=', 'course-of-action')])
+    filter_list = FilterSet(filters)
+    filter_list.add(Filter('type', '=', 'course-of-action'))
     return query(filter_list)
 
 
@@ -192,7 +195,8 @@ def identities(filters=None):
             the query.
 
     """
-    filter_list = _assemble_filters(filters, [Filter('type', '=', 'identity')])
+    filter_list = FilterSet(filters)
+    filter_list.add(Filter('type', '=', 'identity'))
     return query(filter_list)
 
 
@@ -204,7 +208,8 @@ def indicators(filters=None):
             the query.
 
     """
-    filter_list = _assemble_filters(filters, [Filter('type', '=', 'indicator')])
+    filter_list = FilterSet(filters)
+    filter_list.add(Filter('type', '=', 'indicator'))
     return query(filter_list)
 
 
@@ -216,7 +221,8 @@ def intrusion_sets(filters=None):
             the query.
 
     """
-    filter_list = _assemble_filters(filters, [Filter('type', '=', 'intrusion-set')])
+    filter_list = FilterSet(filters)
+    filter_list.add(Filter('type', '=', 'intrusion-set'))
     return query(filter_list)
 
 
@@ -228,7 +234,8 @@ def malware(filters=None):
             the query.
 
     """
-    filter_list = _assemble_filters(filters, [Filter('type', '=', 'malware')])
+    filter_list = FilterSet(filters)
+    filter_list.add(Filter('type', '=', 'malware'))
     return query(filter_list)
 
 
@@ -240,7 +247,8 @@ def observed_data(filters=None):
             the query.
 
     """
-    filter_list = _assemble_filters(filters, [Filter('type', '=', 'observed-data')])
+    filter_list = FilterSet(filters)
+    filter_list.add(Filter('type', '=', 'observed-data'))
     return query(filter_list)
 
 
@@ -252,7 +260,8 @@ def reports(filters=None):
             the query.
 
     """
-    filter_list = _assemble_filters(filters, [Filter('type', '=', 'report')])
+    filter_list = FilterSet(filters)
+    filter_list.add(Filter('type', '=', 'report'))
     return query(filter_list)
 
 
@@ -264,7 +273,8 @@ def threat_actors(filters=None):
             the query.
 
     """
-    filter_list = _assemble_filters(filters, [Filter('type', '=', 'threat-actor')])
+    filter_list = FilterSet(filters)
+    filter_list.add(Filter('type', '=', 'threat-actor'))
     return query(filter_list)
 
 
@@ -276,7 +286,8 @@ def tools(filters=None):
             the query.
 
     """
-    filter_list = _assemble_filters(filters, [Filter('type', '=', 'tool')])
+    filter_list = FilterSet(filters)
+    filter_list.add(Filter('type', '=', 'tool'))
     return query(filter_list)
 
 
@@ -288,5 +299,6 @@ def vulnerabilities(filters=None):
             the query.
 
     """
-    filter_list = _assemble_filters(filters, [Filter('type', '=', 'vulnerability')])
+    filter_list = FilterSet(filters)
+    filter_list.add(Filter('type', '=', 'vulnerability'))
     return query(filter_list)