diff --git a/apps/accounts/views.py b/apps/accounts/views.py
index 6c4aac147cd207ff4956eaa0d8a6527a300470c9..4a6ee5f6792d46683e7af0ac3b0152fb796cba6c 100644
--- a/apps/accounts/views.py
+++ b/apps/accounts/views.py
@@ -65,7 +65,7 @@ class AccountViewSet(viewsets.ModelViewSet):
 
         if User.objects.filter(username=username).exists():
             return Response(
-                {"username" : ["User with that username already exists."]},
+                {"username": ["User with that username already exists."]},
                 status=status.HTTP_409_CONFLICT
             )
 
diff --git a/apps/cases/tests/test_units/test_investigation_cases.py b/apps/cases/tests/test_units/test_investigation_cases.py
index 1552dbfa89c74e508939ac17cad64e49f2e7b670..dbf8ff41197a788d7c24886415c4ffaa2367f769 100644
--- a/apps/cases/tests/test_units/test_investigation_cases.py
+++ b/apps/cases/tests/test_units/test_investigation_cases.py
@@ -111,6 +111,24 @@ class InvestigationCaseViewTest(APITestCase):
         self.assertIn(str(self.reference_case.case_subject.id), response_string)
         self.assertIn(str(self.reference_case.author.id), response_string)
 
+    def test_list_all_investigation_cases_success(self):
+        url = self.BASE_URL + "?include_positive=true"
+
+        response = self.client.get(url)
+        self.assertEqual(response.status_code, status.HTTP_200_OK)
+
+        response_string = response.rendered_content.decode("utf-8")
+
+        self.assertIn('"count":2', response_string)
+        self.assertIn('"next":null', response_string)
+        self.assertIn('"previous":null', response_string)
+        self.assertIn(str(self.case.id), response_string)
+        self.assertIn(str(self.case.case_subject.id), response_string)
+        self.assertIn(str(self.case.author.id), response_string)
+        self.assertIn(str(self.reference_case.id), response_string)
+        self.assertIn(str(self.reference_case.case_subject.id), response_string)
+        self.assertIn(str(self.reference_case.author.id), response_string)
+
     def test_retrieve_investigation_case_fails_on_deleted_subject(self):
         url = self.BASE_URL + str(self.other_deleted_case.id) + "/"
 
diff --git a/apps/cases/views.py b/apps/cases/views.py
index ab9af94209f6530b7a563c40100e3f3f0ac43c48..541c12d1aee1c6463257cfb7a961b777ff9cf44d 100644
--- a/apps/cases/views.py
+++ b/apps/cases/views.py
@@ -68,6 +68,9 @@ class InvestigationCaseViewSet(viewsets.ModelViewSet):
 
     def get_queryset(self):
         if self.action == 'list':
+            query_include_positive = self.request.query_params.get('include_positive', None)
+            if query_include_positive is not None:
+                return self.queryset
             return self.queryset.filter(Q(outcome__isnull=True) | Q(outcome__icontains="-"))
         return self.queryset