diff --git a/src/deltacode/__init__.py b/src/deltacode/__init__.py
index 6b7c1a55..018a8ef9 100644
--- a/src/deltacode/__init__.py
+++ b/src/deltacode/__init__.py
@@ -27,6 +27,7 @@
 
 from collections import OrderedDict
 
+from deltacode.models import File
 from deltacode.models import Scan
 from deltacode import utils
 
@@ -42,7 +43,15 @@ class DeltaCode(object):
     def __init__(self, new_path, old_path):
         self.new = Scan(new_path)
         self.old = Scan(old_path)
-        self.deltas = self.determine_delta()
+        self.deltas = OrderedDict([
+            ('added', []),
+            ('removed', []),
+            ('modified', []),
+            ('unmodified', [])
+        ])
+
+        if self.new.path != '' and self.old.path != '':
+            self.determine_delta()
 
     def align_scan(self):
         """
@@ -65,16 +74,6 @@ def determine_delta(self):
         the objects under the keys 'added', 'modified', 'removed' or 'unmodified'.
         Return None if no File objects can be loaded from either scan.
         """
-        if self.new.files is None or self.old.files is None:
-            return None
-
-        deltas = OrderedDict([
-            ('added', []),
-            ('removed', []),
-            ('modified', []),
-            ('unmodified', [])
-        ])
-
         # align scan and create our index
         self.align_scan()
         new_index = self.new.index_files()
@@ -95,7 +94,7 @@ def determine_delta(self):
                 try:
                     delta_old_files = old_index[path]
                 except KeyError:
-                    deltas['added'].append(Delta(new_file, None, 'added'))
+                    self.deltas['added'].append(Delta(new_file, None, 'added'))
                     continue
 
                 # at this point, we have a delta_old_file.
@@ -104,11 +103,11 @@ def determine_delta(self):
                 for f in delta_old_files:
                     # TODO: make sure sha1 is NOT empty
                     if new_file.sha1 == f.sha1:
-                        deltas['unmodified'].append(Delta(new_file, f, 'unmodified'))
+                        self.deltas['unmodified'].append(Delta(new_file, f, 'unmodified'))
                         continue
                     else:
                         delta = Delta(new_file, f, 'modified')
-                        deltas['modified'].append(delta)
+                        self.deltas['modified'].append(delta)
 
         # now time to find the added.
         for path, old_files in old_index.items():
@@ -122,15 +121,13 @@ def determine_delta(self):
                     # This file already classified as 'modified' or 'unmodified' so do nothing
                     new_index[path]
                 except KeyError:
-                    deltas['removed'].append(Delta(None, old_file, 'removed'))
+                    self.deltas['removed'].append(Delta(None, old_file, 'removed'))
                     continue
 
         # make sure everything is accounted for
         assert new_files_to_visit == 0
         assert old_files_to_visit == 0
 
-        return deltas
-
     def get_stats(self):
         """
         Given a list of Delta objects, return a 'counts' dictionary keyed by
@@ -152,9 +149,6 @@ def to_dict(self):
         objects grouping the objects under the keys 'added', 'removed',
         'modified' or 'unmodified'.
         """
-        if self.deltas is None:
-            return
-
         return OrderedDict([
             ('added', [d.to_dict() for d in self.deltas.get('added')]),
             ('removed', [d.to_dict() for d in self.deltas.get('removed')]),
@@ -170,10 +164,9 @@ class Delta(object):
     'added', 'modified', 'removed' or 'unmodified'.
     """
     def __init__(self, new_file=None, old_file=None, delta_type=None):
-        # TODO: add check to ensure both are File objects
-        self.new_file = new_file
-        self.old_file = old_file
-        self.category = delta_type
+        self.new_file = new_file if new_file else File()
+        self.old_file = old_file if old_file else File()
+        self.category = delta_type if delta_type else ''
 
         # Change the Delta object's 'category' attribute to
         # 'license change' if a substantial license change has been detected.
@@ -187,9 +180,6 @@ def _license_diff(self, cutoff_score=50):
         'license change' if those details differ and the cutoff score test is
         satisfied.
         """
-        if not self.new_file or not self.old_file:
-            return
-
         new_licenses = self.new_file.licenses or []
         new_keys = set(l.key for l in new_licenses if l.score >= cutoff_score)
 
@@ -204,9 +194,6 @@ def to_dict(self):
         Check the 'category' attribute of the Delta object and return an
         OrderedDict comprising the 'category' and 'path' of the object.
         """
-        if self.new_file is None and self.old_file is None:
-            return
-
         if self.category == 'added':
             return OrderedDict([
                 ('category', 'added'),
diff --git a/src/deltacode/cli.py b/src/deltacode/cli.py
index 629fd038..8e4e708f 100644
--- a/src/deltacode/cli.py
+++ b/src/deltacode/cli.py
@@ -78,7 +78,7 @@ def cli(new, old, csv_file, json_file):
     option is selected, print the JSON results to the console.
     """
     # do the delta
-    delta = DeltaCode(new, old)
+    delta = DeltaCode(new, old).determine_delta()
 
     # output to csv
     if csv_file:
diff --git a/src/deltacode/models.py b/src/deltacode/models.py
index d8bf91f9..be1fc99e 100644
--- a/src/deltacode/models.py
+++ b/src/deltacode/models.py
@@ -38,10 +38,19 @@ class Scan(object):
     selected key.
     """
     def __init__(self, path=''):
-        self.path = '' if path is None else path
-        self.files_count = self.get_files_count(self.path)
-        self.files = self.load_files(self.path)
-        self.options = self.get_options(self.path)
+        if path is None:
+            path = ''
+
+        if not self.is_valid_scan(path):
+            self.path = ''
+            self.files_count = 0
+            self.files = []
+            self.options = {}
+        else:
+            self.path = path
+            self.files_count = self.get_files_count(path)
+            self.files = self.load_files(path)
+            self.options = self.get_options(path)
 
     def get_options(self, path):
         """
@@ -145,18 +154,15 @@ class File(object):
     File object created from an ABCD formatted 'file' dictionary.
     """
     def __init__(self, dictionary={}):
-        self.path = dictionary.get('path')
-        self.type = dictionary.get('type')
-        self.name = dictionary.get('name')
-        self.size = dictionary.get('size')
-        self.sha1 = dictionary.get('sha1')
+        self.path = dictionary.get('path', '')
+        self.type = dictionary.get('type', '')
+        self.name = dictionary.get('name', '')
+        self.size = dictionary.get('size', '')
+        self.sha1 = dictionary.get('sha1', '')
         self.original_path = ''
-        self.licenses = self.get_licenses(dictionary)
+        self.licenses = self.get_licenses(dictionary) if dictionary.get('licenses') else []
 
     def get_licenses(self, dictionary):
-        if dictionary.get('licenses') == None:
-            return None
-
         if dictionary.get('licenses') == []:
             return []
         else:
@@ -173,7 +179,7 @@ def to_dict(self):
         ])
 
         # TODO: disable this for now due to high memory usage
-        #if self.licenses:
+        # if self.licenses:
         #    d['licenses'] = [l.to_dict() for l in self.licenses]
 
         return d
diff --git a/tests/test_deltacode.py b/tests/test_deltacode.py
index 7cb0508c..038d4da2 100644
--- a/tests/test_deltacode.py
+++ b/tests/test_deltacode.py
@@ -345,7 +345,7 @@ def test_DeltaCode_to_dict_empty(self):
 
         result = delta.to_dict()
 
-        assert result == None
+        assert result == OrderedDict([('added', []), ('removed', []), ('modified', []), ('unmodified', [])])
 
     def test_DeltaCode_invalid_paths(self):
         test_path_1 = '/some/invalid/path/1.json'
@@ -353,41 +353,40 @@ def test_DeltaCode_invalid_paths(self):
 
         result = DeltaCode(test_path_1, test_path_2)
 
-        assert result.new.path == '/some/invalid/path/1.json'
-        assert result.new.files_count == None
-        assert result.new.files == None
+        assert result.new.path == ''
+        assert result.new.files_count == 0
+        assert result.new.files == []
 
-        assert result.old.path == '/some/invalid/path/2.json'
-        assert result.new.files_count == None
-        assert result.old.files == None
+        assert result.old.path == ''
+        assert result.old.files_count == 0
+        assert result.old.files == []
 
-        assert result.deltas == None
+        assert result.deltas == OrderedDict([('added', []), ('removed', []), ('modified', []), ('unmodified', [])])
 
     def test_DeltaCode_empty_paths(self):
         result = DeltaCode('', '')
 
         assert result.new.path == ''
-        assert result.new.files_count == None
-        assert result.new.files == None
+        assert result.new.files_count == 0
+        assert result.new.files == []
 
         assert result.old.path == ''
-        assert result.new.files_count == None
-        assert result.old.files == None
+        assert result.old.files_count == 0
+        assert result.old.files == []
 
-        assert result.deltas == None
+        assert result.deltas == OrderedDict([('added', []), ('removed', []), ('modified', []), ('unmodified', [])])
 
     def test_DeltaCode_None_paths(self):
         result = DeltaCode(None, None)
 
         assert result.new.path == ''
-        assert result.new.files_count == None
-        assert result.new.files == None
+        assert result.new.files_count == 0
+        assert result.new.files == []
 
         assert result.old.path == ''
-        assert result.new.files_count == None
-        assert result.old.files == None
-
-        assert result.deltas == None
+        assert result.old.files_count == 0
+        assert result.old.files == []
+        assert result.deltas == OrderedDict([('added', []), ('removed', []), ('modified', []), ('unmodified', [])])
 
     def test_Delta_license_diff_new_no_license_info(self):
         new_file = models.File({'path': 'new/path.txt'})
@@ -493,9 +492,9 @@ def test_Delta_license_diff_one_None(self):
     def test_Delta_license_diff_None_files(self):
         delta = deltacode.Delta(None, None, None)
 
-        assert delta.new_file == None
-        assert delta.old_file == None
-        assert delta.category == None
+        assert type(delta.new_file) == type(models.File())
+        assert type(delta.old_file) == type(models.File())
+        assert delta.category == ''
 
     def test_DeltaCode_license_modified_low_score(self):
         new_scan = self.get_test_loc('deltacode/scan_modified_new_license_added_low_score.json')
@@ -678,7 +677,7 @@ def test_Delta_to_dict_unmodified(self):
     def test_Delta_to_dict_empty(self):
         delta = deltacode.Delta()
 
-        assert delta.to_dict() == None
+        assert delta.to_dict() == OrderedDict([('category', 'unmodified'), ('path', '')])
 
     def test_Delta_create_object_removed(self):
         new = None
@@ -686,7 +685,7 @@ def test_Delta_create_object_removed(self):
 
         delta = deltacode.Delta(new, old, 'removed')
 
-        assert delta.new_file == None
+        assert type(delta.new_file) == type(models.File())
         assert delta.old_file.path == 'path/removed.txt'
         assert delta.category == 'removed'
 
@@ -697,7 +696,7 @@ def test_Delta_create_object_added(self):
         delta = deltacode.Delta(new, old, 'added')
 
         assert delta.new_file.path == 'path/added.txt'
-        assert delta.old_file == None
+        assert type(delta.old_file) == type(models.File())
         assert delta.category == 'added'
 
     def test_Delta_create_object_modified(self):
@@ -727,6 +726,6 @@ def test_Delta_create_object_unmodified(self):
     def test_Delta_create_object_empty(self):
         delta = deltacode.Delta()
 
-        assert delta.new_file == None
-        assert delta.old_file == None
-        assert delta.category == None
+        assert type(delta.new_file) == type(models.File())
+        assert type(delta.old_file) == type(models.File())
+        assert delta.category == ''
diff --git a/tests/test_models.py b/tests/test_models.py
index 483ed12f..c6a895c4 100644
--- a/tests/test_models.py
+++ b/tests/test_models.py
@@ -344,26 +344,26 @@ def test_Scan_invalid_path(self):
 
         result = models.Scan(test_path)
 
-        assert result.path == '/some/invalid/path.json'
-        assert result.files_count == None
-        assert result.files == None
-        assert result.options == None
+        assert result.path == ''
+        assert result.files_count == 0
+        assert result.files == []
+        assert result.options == {}
 
     def test_Scan_empty_path(self):
         result = models.Scan('')
 
         assert result.path == ''
-        assert result.files_count == None
-        assert result.files == None
-        assert result.options == None
+        assert result.files_count == 0
+        assert result.files == []
+        assert result.options == {}
 
     def test_Scan_None_path(self):
         result = models.Scan(None)
 
         assert result.path == ''
-        assert result.files_count == None
-        assert result.files == None
-        assert result.options == None
+        assert result.files_count == 0
+        assert result.files == []
+        assert result.options == {}
 
     def test_License_to_dict_simple(self):
         data = {
@@ -549,11 +549,11 @@ def test_File_to_dict_empty(self):
         empty_file = models.File()
 
         expected = {
-            'path': None,
-            'type': None,
-            'name': None,
-            'size': None,
-            'sha1': None,
+            'path': '',
+            'type': '',
+            'name': '',
+            'size': '',
+            'sha1': '',
             'original_path': ''
         }
 
@@ -621,6 +621,29 @@ def test_File_create_object_license_none(self):
         assert '26d82f1931cbdbd83c2a6871b2cecd5cbcc8c26b' == result.sha1
         assert [] == result.licenses
 
+    def test_File_create_object_license_missing(self):
+        data = {
+            'path': 'a/b/file1.txt',
+            'type': 'file',
+            'name': 'file1.txt',
+            'size': 20,
+            'sha1': '26d82f1931cbdbd83c2a6871b2cecd5cbcc8c26b',
+        }
+
+        result = models.File(data)
+
+        assert [] == result.licenses
+
+    def test_File_empty(self):
+        empty_file = models.File()
+
+        assert empty_file.path == ''
+        assert empty_file.type == ''
+        assert empty_file.name == ''
+        assert empty_file.size == ''
+        assert empty_file.sha1 == ''
+        assert empty_file.licenses == []
+
     def test_File_create_object(self):
         data = {
             'path': 'a/b/file1.txt',