diff --git a/rest_framework/authtoken/views.py b/rest_framework/authtoken/views.py
index 4f90d9528..7c03cb766 100644
--- a/rest_framework/authtoken/views.py
+++ b/rest_framework/authtoken/views.py
@@ -2,7 +2,6 @@ from rest_framework.views import APIView
 from rest_framework import status
 from rest_framework import parsers
 from rest_framework import renderers
-from rest_framework import exceptions
 from rest_framework.response import Response
 from rest_framework.authtoken.models import Token
 from rest_framework.authtoken.serializers import AuthTokenSerializer
@@ -21,7 +20,7 @@ class ObtainAuthToken(APIView):
         if serializer.is_valid():
             token, created = Token.objects.get_or_create(user=serializer.object['user'])
             return Response({'token': token.key})
-        raise exceptions.TokenAuthenticationError(serializer.errors)
+        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
 
 
 obtain_auth_token = ObtainAuthToken.as_view()
diff --git a/rest_framework/exceptions.py b/rest_framework/exceptions.py
index 50e2959e0..dc5f686e9 100644
--- a/rest_framework/exceptions.py
+++ b/rest_framework/exceptions.py
@@ -27,20 +27,6 @@ class ParseError(APIException):
     default_detail = 'Malformed request.'
 
 
-class DeserializeError(APIException):
-    status_code = status.HTTP_400_BAD_REQUEST
-
-    def __init__(self, errors):
-        self.data = dict(errors)
-
-
-class TokenAuthenticationError(DeserializeError):
-    """Raised when incorrect data is posted during Token Authentication."""
-    # TODO: Change status code to HTTP_401
-    # TODO: Make data look like {'detail': 'Reason of failure'}
-    pass
-
-
 class AuthenticationFailed(APIException):
     status_code = status.HTTP_401_UNAUTHORIZED
     default_detail = 'Incorrect authentication credentials.'
diff --git a/rest_framework/mixins.py b/rest_framework/mixins.py
index b190e5728..f11def6d4 100644
--- a/rest_framework/mixins.py
+++ b/rest_framework/mixins.py
@@ -7,7 +7,7 @@ which allows mixin classes to be composed in interesting ways.
 from __future__ import unicode_literals
 
 from django.http import Http404
-from rest_framework import status, exceptions
+from rest_framework import status
 from rest_framework.response import Response
 from rest_framework.request import clone_request
 import warnings
@@ -55,7 +55,7 @@ class CreateModelMixin(object):
             return Response(serializer.data, status=status.HTTP_201_CREATED,
                             headers=headers)
 
-        raise exceptions.DeserializeError(serializer.errors)
+        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
 
     def get_success_headers(self, data):
         try:
@@ -132,7 +132,7 @@ class UpdateModelMixin(object):
             self.post_save(self.object, created=created)
             return Response(serializer.data, status=success_status_code)
 
-        raise exceptions.DeserializeError(serializer.errors)
+        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
 
     def partial_update(self, request, *args, **kwargs):
         kwargs['partial'] = True
diff --git a/rest_framework/tests/test_views.py b/rest_framework/tests/test_views.py
index 095788b42..aa1bef7a9 100644
--- a/rest_framework/tests/test_views.py
+++ b/rest_framework/tests/test_views.py
@@ -1,7 +1,6 @@
 from __future__ import unicode_literals
 
 import copy
-import warnings
 
 from django.test import TestCase
 from django.test.client import RequestFactory
@@ -94,10 +93,7 @@ class ClassBasedViewIntegrationTests(TestCase):
     def test_return_400_error(self):
         request = factory.post('/', '{"return_400_error": true}',
                                content_type='application/json')
-        with warnings.catch_warnings(record=True) as w:
-            warnings.simplefilter('always')
-            response = self.view(request)
-            self.assertEqual(len(w), 1)
+        response = self.view(request)
         expected = {
             'detail': 'Bad request'
         }
@@ -146,10 +142,7 @@ class FunctionBasedViewIntegrationTests(TestCase):
     def test_return_400_error(self):
         request = factory.post('/', '{"return_400_error": true}',
                                content_type='application/json')
-        with warnings.catch_warnings(record=True) as w:
-            warnings.simplefilter('always')
-            response = self.view(request)
-            self.assertEqual(len(w), 1)
+        response = self.view(request)
         expected = {
             'detail': 'Bad request'
         }
diff --git a/rest_framework/views.py b/rest_framework/views.py
index 1304cebe7..4cb917b72 100644
--- a/rest_framework/views.py
+++ b/rest_framework/views.py
@@ -3,8 +3,6 @@ Provides an APIView class that is the base of all views in REST framework.
 """
 from __future__ import unicode_literals
 
-import warnings
-
 from django.http import HttpResponse
 from django.utils.datastructures import SortedDict
 from django.views.decorators.csrf import csrf_exempt
@@ -291,11 +289,6 @@ class APIView(View):
 
             response = handler(request, *args, **kwargs)
 
-            if response.status_code >= 400:
-                warnings.warn('Status code >= 400 returned. You should raise'
-                              ' `rest_framework.exceptions.APIException`'
-                              ' instead.', stacklevel=2)
-
         except Exception as exc:
             response = self.handle_exception(exc)