diff --git a/openid/extensions/draft/pape5.py b/openid/extensions/draft/pape5.py
index 497df154..5826f651 100644
--- a/openid/extensions/draft/pape5.py
+++ b/openid/extensions/draft/pape5.py
@@ -13,12 +13,12 @@
     'AUTH_PHISHING_RESISTANT',
     'AUTH_MULTI_FACTOR',
     'AUTH_MULTI_FACTOR_PHYSICAL',
-    'AUTH_NONE',
     'LEVELS_NIST',
     'LEVELS_JISA',
     ]
 
 from openid.extension import Extension
+import warnings
 import re
 
 ns_uri = "http://specs.openid.net/extensions/pape/1.0"
@@ -271,6 +271,9 @@ def preferredTypes(self, supported_types):
 class Response(PAPEExtension):
     """A Provider Authentication Policy response, sent from a provider
     to a relying party
+
+    @ivar auth_policies: List of authentication policies conformed to
+        by this OpenID assertion, represented as policy URIs
     """
 
     ns_alias = 'pape'
@@ -338,6 +341,10 @@ def addPolicyURI(self, policy_uri):
             authentication.
         @see: http://openid.net/specs/openid-provider-authentication-policy-extension-1_0-01.html#auth_policies
         """
+        if policy_uri == AUTH_NONE:
+            raise RuntimeError(
+                'To send no policies, do not set any on the response.')
+
         if policy_uri not in self.auth_policies:
             self.auth_policies.append(policy_uri)
 
@@ -382,8 +389,28 @@ def parseExtensionArgs(self, args, strict=False):
             this object.
         """
         policies_str = args.get('auth_policies')
-        if policies_str and policies_str != 'none':
-            self.auth_policies = policies_str.split(' ')
+        if policies_str:
+            auth_policies = policies_str.split(' ')
+        elif strict:
+            raise ValueError('Missing auth_policies')
+        else:
+            auth_policies = []
+
+        if (len(auth_policies) > 1 and strict and AUTH_NONE in auth_policies):
+            raise ValueError('Got some auth policies, as well as the special '
+                             '"none" URI: %r' % (auth_policies,))
+
+        if 'none' in auth_policies:
+            msg = '"none" used as a policy URI (see PAPE draft < 5)'
+            if strict:
+                raise ValueError(msg)
+            else:
+                warnings.warn(msg, stacklevel=2)
+
+        auth_policies = [u for u in auth_policies
+                         if u not in ['none', AUTH_NONE]]
+
+        self.auth_policies = auth_policies
 
         for (key, val) in args.iteritems():
             if key.startswith('auth_level.'):
@@ -418,7 +445,7 @@ def getExtensionArgs(self):
         """
         if len(self.auth_policies) == 0:
             ns_args = {
-                'auth_policies':'none',
+                'auth_policies': AUTH_NONE,
             }
         else:
             ns_args = {
diff --git a/openid/test/test_pape_draft5.py b/openid/test/test_pape_draft5.py
index a61aa685..acd13de3 100644
--- a/openid/test/test_pape_draft5.py
+++ b/openid/test/test_pape_draft5.py
@@ -3,6 +3,10 @@
 from openid.message import *
 from openid.server import server
 
+import warnings
+warnings.filterwarnings('ignore', module=__name__,
+                        message='"none" used as a policy URI')
+
 import unittest
 
 class PapeRequestTestCase(unittest.TestCase):
@@ -246,8 +250,11 @@ def test_add_policy_uri(self):
                               pape.AUTH_PHISHING_RESISTANT],
                              self.resp.auth_policies)
 
+        self.failUnlessRaises(RuntimeError, self.resp.addPolicyURI,
+                              pape.AUTH_NONE)
+
     def test_getExtensionArgs(self):
-        self.failUnlessEqual({'auth_policies': 'none'},
+        self.failUnlessEqual({'auth_policies': pape.AUTH_NONE},
                              self.resp.getExtensionArgs())
         self.resp.addPolicyURI('http://uri')
         self.failUnlessEqual({'auth_policies': 'http://uri'},
@@ -280,11 +287,52 @@ def test_parseExtensionArgs(self):
         self.failUnlessEqual(['http://foo','http://bar'],
                              self.resp.auth_policies)
 
+    def test_parseExtensionArgs_valid_none(self):
+        args = {'auth_policies': pape.AUTH_NONE}
+        self.resp.parseExtensionArgs(args)
+        self.failUnlessEqual([], self.resp.auth_policies)
+
+    def test_parseExtensionArgs_old_none(self):
+        args = {'auth_policies': 'none'}
+        self.resp.parseExtensionArgs(args)
+        self.failUnlessEqual([], self.resp.auth_policies)
+
+    def test_parseExtensionArgs_old_none_strict(self):
+        args = {'auth_policies': 'none'}
+        self.failUnlessRaises(ValueError,
+                              self.resp.parseExtensionArgs, args, strict=True)
+
     def test_parseExtensionArgs_empty(self):
         self.resp.parseExtensionArgs({})
         self.failUnlessEqual(None, self.resp.auth_time)
         self.failUnlessEqual([], self.resp.auth_policies)
 
+    def test_parseExtensionArgs_empty_strict(self):
+        self.failUnlessRaises(ValueError,
+                              self.resp.parseExtensionArgs, {}, strict=True)
+
+    def test_parseExtensionArgs_ignore_superfluous_none(self):
+        policies = [pape.AUTH_NONE, pape.AUTH_MULTI_FACTOR_PHYSICAL]
+
+        args = {
+            'auth_policies': ' '.join(policies),
+            }
+
+        self.resp.parseExtensionArgs(args, strict=False)
+
+        self.assertEqual([pape.AUTH_MULTI_FACTOR_PHYSICAL],
+                         self.resp.auth_policies)
+
+    def test_parseExtensionArgs_none_strict(self):
+        policies = [pape.AUTH_NONE, pape.AUTH_MULTI_FACTOR_PHYSICAL]
+
+        args = {
+            'auth_policies': ' '.join(policies),
+            }
+
+        self.failUnlessRaises(ValueError, self.resp.parseExtensionArgs,
+                              args, strict=True)
+
     def test_parseExtensionArgs_strict_bogus1(self):
         args = {'auth_policies': 'http://foo http://bar',
                 'auth_time': 'yesterday'}