diff --git a/pkg/apiserver/authz.go b/pkg/apiserver/authz.go
index e9deaad529132..7a19f2d4fcd77 100644
--- a/pkg/apiserver/authz.go
+++ b/pkg/apiserver/authz.go
@@ -42,8 +42,8 @@ type Attributes struct {
 // It is useful in tests and when using kubernetes in an open manner.
 type alwaysAllowAuthorizer struct{}
 
-func (alwaysAllowAuthorizer) Authorize(a authorizer.Attributes) (err error) {
-	return nil
+func (alwaysAllowAuthorizer) Authorize(a authorizer.Attributes) (authorized bool, reason string, err error) {
+	return true, "", nil
 }
 
 func NewAlwaysAllowAuthorizer() authorizer.Authorizer {
@@ -55,14 +55,27 @@ func NewAlwaysAllowAuthorizer() authorizer.Authorizer {
 // It is useful in unit tests to force an operation to be forbidden.
 type alwaysDenyAuthorizer struct{}
 
-func (alwaysDenyAuthorizer) Authorize(a authorizer.Attributes) (err error) {
-	return errors.New("Everything is forbidden.")
+func (alwaysDenyAuthorizer) Authorize(a authorizer.Attributes) (authorized bool, reason string, err error) {
+	return false, "Everything is forbidden.", nil
 }
 
 func NewAlwaysDenyAuthorizer() authorizer.Authorizer {
 	return new(alwaysDenyAuthorizer)
 }
 
+// alwaysFailAuthorizer is an implementation of authorizer.Attributes
+// which always says no to an authorization request.
+// It is useful in unit tests to force an operation to fail with error.
+type alwaysFailAuthorizer struct{}
+
+func (alwaysFailAuthorizer) Authorize(a authorizer.Attributes) (authorized bool, reason string, err error) {
+	return false, "", errors.New("Authorization failure.")
+}
+
+func NewAlwaysFailAuthorizer() authorizer.Authorizer {
+	return new(alwaysFailAuthorizer)
+}
+
 const (
 	ModeAlwaysAllow string = "AlwaysAllow"
 	ModeAlwaysDeny  string = "AlwaysDeny"
diff --git a/pkg/apiserver/authz_test.go b/pkg/apiserver/authz_test.go
index 1c474363d92e1..bc9b6ebba8f24 100644
--- a/pkg/apiserver/authz_test.go
+++ b/pkg/apiserver/authz_test.go
@@ -24,8 +24,8 @@ import (
 // and always return nil.
 func TestNewAlwaysAllowAuthorizer(t *testing.T) {
 	aaa := NewAlwaysAllowAuthorizer()
-	if result := aaa.Authorize(nil); result != nil {
-		t.Errorf("AlwaysAllowAuthorizer.Authorize did not return nil. (%s)", result)
+	if authorized, _, _ := aaa.Authorize(nil); !authorized {
+		t.Errorf("AlwaysAllowAuthorizer.Authorize did not authorize successfully.")
 	}
 }
 
@@ -33,7 +33,7 @@ func TestNewAlwaysAllowAuthorizer(t *testing.T) {
 // and always return an error as everything is forbidden.
 func TestNewAlwaysDenyAuthorizer(t *testing.T) {
 	ada := NewAlwaysDenyAuthorizer()
-	if result := ada.Authorize(nil); result == nil {
+	if authorized, _, _ := ada.Authorize(nil); authorized {
 		t.Errorf("AlwaysDenyAuthorizer.Authorize returned nil instead of error.")
 	}
 }
diff --git a/pkg/apiserver/errors.go b/pkg/apiserver/errors.go
index 9f10c5c9cff58..7f778b7720df1 100644
--- a/pkg/apiserver/errors.go
+++ b/pkg/apiserver/errors.go
@@ -88,6 +88,13 @@ func forbidden(w http.ResponseWriter, req *http.Request) {
 	fmt.Fprintf(w, "Forbidden: %#v", req.RequestURI)
 }
 
+// internalError renders a simple internal error
+func internalError(w http.ResponseWriter, req *http.Request, err error) {
+	w.WriteHeader(http.StatusInternalServerError)
+	fmt.Fprintf(w, "Internal Server Error: %#v", req.RequestURI)
+	runtime.HandleError(err)
+}
+
 // errAPIPrefixNotFound indicates that a RequestInfo resolution failed because the request isn't under
 // any known API prefixes
 type errAPIPrefixNotFound struct {
diff --git a/pkg/apiserver/handlers.go b/pkg/apiserver/handlers.go
index 0b064da680c99..4f593127361a5 100644
--- a/pkg/apiserver/handlers.go
+++ b/pkg/apiserver/handlers.go
@@ -446,8 +446,13 @@ func WithImpersonation(handler http.Handler, requestContextMapper api.RequestCon
 			actingAsAttributes.Name = name
 		}
 
-		err := a.Authorize(actingAsAttributes)
+		authorized, reason, err := a.Authorize(actingAsAttributes)
 		if err != nil {
+			internalError(w, req, err)
+			return
+		}
+		if !authorized {
+			glog.V(4).Infof("Forbidden: %#v, Reason: %s", req.RequestURI, reason)
 			forbidden(w, req)
 			return
 		}
@@ -480,12 +485,17 @@ func WithImpersonation(handler http.Handler, requestContextMapper api.RequestCon
 // WithAuthorizationCheck passes all authorized requests on to handler, and returns a forbidden error otherwise.
 func WithAuthorizationCheck(handler http.Handler, getAttribs RequestAttributeGetter, a authorizer.Authorizer) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
-		err := a.Authorize(getAttribs.GetAttribs(req))
-		if err == nil {
-			handler.ServeHTTP(w, req)
+		authorized, reason, err := a.Authorize(getAttribs.GetAttribs(req))
+		if err != nil {
+			internalError(w, req, err)
 			return
 		}
-		forbidden(w, req)
+		if !authorized {
+			glog.V(4).Infof("Forbidden: %#v, Reason: %s", req.RequestURI, reason)
+			forbidden(w, req)
+			return
+		}
+		handler.ServeHTTP(w, req)
 	})
 }
 
diff --git a/pkg/auth/authorizer/abac/abac.go b/pkg/auth/authorizer/abac/abac.go
index ca5ef6c633aa7..75db334e819bd 100644
--- a/pkg/auth/authorizer/abac/abac.go
+++ b/pkg/auth/authorizer/abac/abac.go
@@ -21,7 +21,6 @@ package abac
 
 import (
 	"bufio"
-	"errors"
 	"fmt"
 	"os"
 	"strings"
@@ -222,13 +221,13 @@ func resourceMatches(p api.Policy, a authorizer.Attributes) bool {
 }
 
 // Authorizer implements authorizer.Authorize
-func (pl policyList) Authorize(a authorizer.Attributes) error {
+func (pl policyList) Authorize(a authorizer.Attributes) (bool, string, error) {
 	for _, p := range pl {
 		if matches(*p, a) {
-			return nil
+			return true, "", nil
 		}
 	}
-	return errors.New("No policy matched.")
+	return false, "No policy matched.", nil
 	// TODO: Benchmark how much time policy matching takes with a medium size
 	// policy file, compared to other steps such as encoding/decoding.
 	// Then, add Caching only if needed.
diff --git a/pkg/auth/authorizer/abac/abac_test.go b/pkg/auth/authorizer/abac/abac_test.go
index 4a56b8dc39663..0070fbdea329c 100644
--- a/pkg/auth/authorizer/abac/abac_test.go
+++ b/pkg/auth/authorizer/abac/abac_test.go
@@ -130,12 +130,11 @@ func TestAuthorizeV0(t *testing.T) {
 
 			ResourceRequest: len(tc.NS) > 0 || len(tc.Resource) > 0,
 		}
-		err := a.Authorize(attr)
-		actualAllow := bool(err == nil)
-		if tc.ExpectAllow != actualAllow {
+		authorized, _, _ := a.Authorize(attr)
+		if tc.ExpectAllow != authorized {
 			t.Logf("tc: %v -> attr %v", tc, attr)
 			t.Errorf("%d: Expected allowed=%v but actually allowed=%v\n\t%v",
-				i, tc.ExpectAllow, actualAllow, tc)
+				i, tc.ExpectAllow, authorized, tc)
 		}
 	}
 }
@@ -250,11 +249,10 @@ func TestAuthorizeV1beta1(t *testing.T) {
 			Path:            tc.Path,
 		}
 		// t.Logf("tc %2v: %v -> attr %v", i, tc, attr)
-		err := a.Authorize(attr)
-		actualAllow := bool(err == nil)
-		if tc.ExpectAllow != actualAllow {
+		authorized, _, _ := a.Authorize(attr)
+		if tc.ExpectAllow != authorized {
 			t.Errorf("%d: Expected allowed=%v but actually allowed=%v, for case %+v & %+v",
-				i, tc.ExpectAllow, actualAllow, tc, attr)
+				i, tc.ExpectAllow, authorized, tc, attr)
 		}
 	}
 }
diff --git a/pkg/auth/authorizer/interfaces.go b/pkg/auth/authorizer/interfaces.go
index c44fd4a2b306e..e23ea45960b99 100644
--- a/pkg/auth/authorizer/interfaces.go
+++ b/pkg/auth/authorizer/interfaces.go
@@ -67,12 +67,12 @@ type Attributes interface {
 // zero or more calls to methods of the Attributes interface.  It returns nil when an action is
 // authorized, otherwise it returns an error.
 type Authorizer interface {
-	Authorize(a Attributes) (err error)
+	Authorize(a Attributes) (authorized bool, reason string, err error)
 }
 
-type AuthorizerFunc func(a Attributes) error
+type AuthorizerFunc func(a Attributes) (bool, string, error)
 
-func (f AuthorizerFunc) Authorize(a Attributes) error {
+func (f AuthorizerFunc) Authorize(a Attributes) (bool, string, error) {
 	return f(a)
 }
 
diff --git a/pkg/auth/authorizer/union/union.go b/pkg/auth/authorizer/union/union.go
index 7adbaa512b481..880d8c79eb394 100644
--- a/pkg/auth/authorizer/union/union.go
+++ b/pkg/auth/authorizer/union/union.go
@@ -17,6 +17,8 @@ limitations under the License.
 package union
 
 import (
+	"strings"
+
 	"k8s.io/kubernetes/pkg/auth/authorizer"
 	utilerrors "k8s.io/kubernetes/pkg/util/errors"
 )
@@ -30,16 +32,26 @@ func New(authorizationHandlers ...authorizer.Authorizer) authorizer.Authorizer {
 }
 
 // Authorizes against a chain of authorizer.Authorizer objects and returns nil if successful and returns error if unsuccessful
-func (authzHandler unionAuthzHandler) Authorize(a authorizer.Attributes) error {
-	var errlist []error
+func (authzHandler unionAuthzHandler) Authorize(a authorizer.Attributes) (bool, string, error) {
+	var (
+		errlist    []error
+		reasonlist []string
+	)
 	for _, currAuthzHandler := range authzHandler {
-		err := currAuthzHandler.Authorize(a)
+		authorized, reason, err := currAuthzHandler.Authorize(a)
+
 		if err != nil {
 			errlist = append(errlist, err)
 			continue
 		}
-		return nil
+		if !authorized {
+			if reason != "" {
+				reasonlist = append(reasonlist, reason)
+			}
+			continue
+		}
+		return true, reason, nil
 	}
 
-	return utilerrors.NewAggregate(errlist)
+	return false, strings.Join(reasonlist, "\n"), utilerrors.NewAggregate(errlist)
 }
diff --git a/pkg/auth/authorizer/union/union_test.go b/pkg/auth/authorizer/union/union_test.go
index 32bfbcd5a3593..d6841188ca398 100644
--- a/pkg/auth/authorizer/union/union_test.go
+++ b/pkg/auth/authorizer/union/union_test.go
@@ -17,7 +17,7 @@ limitations under the License.
 package union
 
 import (
-	"errors"
+	"fmt"
 	"testing"
 
 	"k8s.io/kubernetes/pkg/auth/authorizer"
@@ -28,15 +28,14 @@ type mockAuthzHandler struct {
 	err          error
 }
 
-func (mock *mockAuthzHandler) Authorize(a authorizer.Attributes) error {
+func (mock *mockAuthzHandler) Authorize(a authorizer.Attributes) (bool, string, error) {
 	if mock.err != nil {
-		return mock.err
+		return false, "", mock.err
 	}
 	if !mock.isAuthorized {
-		return errors.New("Request unauthorized")
-	} else {
-		return nil
+		return false, "", nil
 	}
+	return true, "", nil
 }
 
 func TestAuthorizationSecondPasses(t *testing.T) {
@@ -44,9 +43,9 @@ func TestAuthorizationSecondPasses(t *testing.T) {
 	handler2 := &mockAuthzHandler{isAuthorized: true}
 	authzHandler := New(handler1, handler2)
 
-	err := authzHandler.Authorize(nil)
-	if err != nil {
-		t.Errorf("Unexpected error: %v", err)
+	authorized, _, _ := authzHandler.Authorize(nil)
+	if !authorized {
+		t.Errorf("Unexpected authorization failure")
 	}
 }
 
@@ -55,9 +54,9 @@ func TestAuthorizationFirstPasses(t *testing.T) {
 	handler2 := &mockAuthzHandler{isAuthorized: false}
 	authzHandler := New(handler1, handler2)
 
-	err := authzHandler.Authorize(nil)
-	if err != nil {
-		t.Errorf("Unexpected error: %v", err)
+	authorized, _, _ := authzHandler.Authorize(nil)
+	if !authorized {
+		t.Errorf("Unexpected authorization failure")
 	}
 }
 
@@ -66,7 +65,18 @@ func TestAuthorizationNonePasses(t *testing.T) {
 	handler2 := &mockAuthzHandler{isAuthorized: false}
 	authzHandler := New(handler1, handler2)
 
-	err := authzHandler.Authorize(nil)
+	authorized, _, _ := authzHandler.Authorize(nil)
+	if authorized {
+		t.Errorf("Expected failed authorization")
+	}
+}
+
+func TestAuthorizationError(t *testing.T) {
+	handler1 := &mockAuthzHandler{err: fmt.Errorf("foo")}
+	handler2 := &mockAuthzHandler{err: fmt.Errorf("foo")}
+	authzHandler := New(handler1, handler2)
+
+	_, _, err := authzHandler.Authorize(nil)
 	if err == nil {
 		t.Errorf("Expected error: %v", err)
 	}
diff --git a/pkg/kubelet/server/server.go b/pkg/kubelet/server/server.go
index cfb3600b5ba7c..38b4dad0b0f2d 100644
--- a/pkg/kubelet/server/server.go
+++ b/pkg/kubelet/server/server.go
@@ -221,8 +221,15 @@ func (s *Server) InstallAuthFilter() {
 		attrs := s.auth.GetRequestAttributes(u, req.Request)
 
 		// Authorize
-		if err := s.auth.Authorize(attrs); err != nil {
-			msg := fmt.Sprintf("Forbidden (user=%s, verb=%s, namespace=%s, resource=%s)", u.GetName(), attrs.GetVerb(), attrs.GetNamespace(), attrs.GetResource())
+		authorized, reason, err := s.auth.Authorize(attrs)
+		if err != nil {
+			msg := fmt.Sprintf("Error (user=%s, verb=%s, namespace=%s, resource=%s)", u.GetName(), attrs.GetVerb(), attrs.GetNamespace(), attrs.GetResource())
+			glog.Errorf(msg, err)
+			resp.WriteErrorString(http.StatusInternalServerError, msg)
+			return
+		}
+		if !authorized {
+			msg := fmt.Sprintf("Forbidden (reason=%s, user=%s, verb=%s, namespace=%s, resource=%s)", reason, u.GetName(), attrs.GetVerb(), attrs.GetNamespace(), attrs.GetResource())
 			glog.V(2).Info(msg)
 			resp.WriteErrorString(http.StatusForbidden, msg)
 			return
diff --git a/pkg/kubelet/server/server_test.go b/pkg/kubelet/server/server_test.go
index 1bc04481f5131..4674a6ae4e897 100644
--- a/pkg/kubelet/server/server_test.go
+++ b/pkg/kubelet/server/server_test.go
@@ -161,7 +161,7 @@ func (fk *fakeKubelet) ListVolumesForPod(podUID types.UID) (map[string]volume.Vo
 type fakeAuth struct {
 	authenticateFunc func(*http.Request) (user.Info, bool, error)
 	attributesFunc   func(user.Info, *http.Request) authorizer.Attributes
-	authorizeFunc    func(authorizer.Attributes) (err error)
+	authorizeFunc    func(authorizer.Attributes) (authorized bool, reason string, err error)
 }
 
 func (f *fakeAuth) AuthenticateRequest(req *http.Request) (user.Info, bool, error) {
@@ -170,7 +170,7 @@ func (f *fakeAuth) AuthenticateRequest(req *http.Request) (user.Info, bool, erro
 func (f *fakeAuth) GetRequestAttributes(u user.Info, req *http.Request) authorizer.Attributes {
 	return f.attributesFunc(u, req)
 }
-func (f *fakeAuth) Authorize(a authorizer.Attributes) (err error) {
+func (f *fakeAuth) Authorize(a authorizer.Attributes) (authorized bool, reason string, err error) {
 	return f.authorizeFunc(a)
 }
 
@@ -204,8 +204,8 @@ func newServerTest() *serverTestFramework {
 		attributesFunc: func(u user.Info, req *http.Request) authorizer.Attributes {
 			return &authorizer.AttributesRecord{User: u}
 		},
-		authorizeFunc: func(a authorizer.Attributes) (err error) {
-			return nil
+		authorizeFunc: func(a authorizer.Attributes) (authorized bool, reason string, err error) {
+			return true, "", nil
 		},
 	}
 	server := NewServer(
@@ -626,12 +626,12 @@ func TestAuthFilters(t *testing.T) {
 			}
 			return expectedAttributes
 		}
-		fw.fakeAuth.authorizeFunc = func(a authorizer.Attributes) (err error) {
+		fw.fakeAuth.authorizeFunc = func(a authorizer.Attributes) (authorized bool, reason string, err error) {
 			calledAuthorize = true
 			if a != expectedAttributes {
 				t.Fatalf("%s: expected attributes %v, got %v", tc.Path, expectedAttributes, a)
 			}
-			return errors.New("Forbidden")
+			return false, "", nil
 		}
 
 		req, err := http.NewRequest(tc.Method, fw.testHTTPServer.URL+tc.Path, nil)
@@ -665,6 +665,44 @@ func TestAuthFilters(t *testing.T) {
 	}
 }
 
+func TestAuthenticationError(t *testing.T) {
+	var (
+		expectedUser       = &user.DefaultInfo{Name: "test"}
+		expectedAttributes = &authorizer.AttributesRecord{User: expectedUser}
+
+		calledAuthenticate = false
+		calledAuthorize    = false
+		calledAttributes   = false
+	)
+
+	fw := newServerTest()
+	defer fw.testHTTPServer.Close()
+	fw.fakeAuth.authenticateFunc = func(req *http.Request) (user.Info, bool, error) {
+		calledAuthenticate = true
+		return expectedUser, true, nil
+	}
+	fw.fakeAuth.attributesFunc = func(u user.Info, req *http.Request) authorizer.Attributes {
+		calledAttributes = true
+		return expectedAttributes
+	}
+	fw.fakeAuth.authorizeFunc = func(a authorizer.Attributes) (authorized bool, reason string, err error) {
+		calledAuthorize = true
+		return false, "", errors.New("Failed")
+	}
+
+	assertHealthFails(t, fw.testHTTPServer.URL+"/healthz", http.StatusInternalServerError)
+
+	if !calledAuthenticate {
+		t.Fatalf("Authenticate was not called")
+	}
+	if !calledAttributes {
+		t.Fatalf("Attributes was not called")
+	}
+	if !calledAuthorize {
+		t.Fatalf("Authorize was not called")
+	}
+}
+
 func TestAuthenticationFailure(t *testing.T) {
 	var (
 		expectedUser       = &user.DefaultInfo{Name: "test"}
@@ -685,9 +723,9 @@ func TestAuthenticationFailure(t *testing.T) {
 		calledAttributes = true
 		return expectedAttributes
 	}
-	fw.fakeAuth.authorizeFunc = func(a authorizer.Attributes) (err error) {
+	fw.fakeAuth.authorizeFunc = func(a authorizer.Attributes) (authorized bool, reason string, err error) {
 		calledAuthorize = true
-		return errors.New("not allowed")
+		return false, "", nil
 	}
 
 	assertHealthFails(t, fw.testHTTPServer.URL+"/healthz", http.StatusUnauthorized)
@@ -723,9 +761,9 @@ func TestAuthorizationSuccess(t *testing.T) {
 		calledAttributes = true
 		return expectedAttributes
 	}
-	fw.fakeAuth.authorizeFunc = func(a authorizer.Attributes) (err error) {
+	fw.fakeAuth.authorizeFunc = func(a authorizer.Attributes) (authorized bool, reason string, err error) {
 		calledAuthorize = true
-		return nil
+		return true, "", nil
 	}
 
 	assertHealthIsOk(t, fw.testHTTPServer.URL+"/healthz")
diff --git a/plugin/pkg/auth/authorizer/rbac/rbac.go b/plugin/pkg/auth/authorizer/rbac/rbac.go
index 087e564a988f3..bfcb49d16c19d 100644
--- a/plugin/pkg/auth/authorizer/rbac/rbac.go
+++ b/plugin/pkg/auth/authorizer/rbac/rbac.go
@@ -34,9 +34,9 @@ type RBACAuthorizer struct {
 	authorizationRuleResolver validation.AuthorizationRuleResolver
 }
 
-func (r *RBACAuthorizer) Authorize(attr authorizer.Attributes) error {
+func (r *RBACAuthorizer) Authorize(attr authorizer.Attributes) (bool, string, error) {
 	if r.superUser != "" && attr.GetUser() != nil && attr.GetUser().GetName() == r.superUser {
-		return nil
+		return true, "", nil
 	}
 
 	ctx := api.WithNamespace(api.WithUser(api.NewContext(), attr.GetUser()), attr.GetNamespace())
@@ -57,7 +57,13 @@ func (r *RBACAuthorizer) Authorize(attr authorizer.Attributes) error {
 		}
 	}
 
-	return validation.ConfirmNoEscalation(ctx, r.authorizationRuleResolver, []rbac.PolicyRule{requestedRule})
+	// TODO(nhlfr): Try to find more lightweight way to check attributes than escalation checks.
+	err := validation.ConfirmNoEscalation(ctx, r.authorizationRuleResolver, []rbac.PolicyRule{requestedRule})
+	if err != nil {
+		return false, err.Error(), nil
+	}
+
+	return true, "", nil
 }
 
 func New(roleRegistry role.Registry, roleBindingRegistry rolebinding.Registry, clusterRoleRegistry clusterrole.Registry, clusterRoleBindingRegistry clusterrolebinding.Registry, superUser string) *RBACAuthorizer {
diff --git a/plugin/pkg/auth/authorizer/rbac/rbac_test.go b/plugin/pkg/auth/authorizer/rbac/rbac_test.go
index 7aaf104dc5bd5..6eefddf0adda9 100644
--- a/plugin/pkg/auth/authorizer/rbac/rbac_test.go
+++ b/plugin/pkg/auth/authorizer/rbac/rbac_test.go
@@ -192,13 +192,13 @@ func TestAuthorizer(t *testing.T) {
 		ruleResolver := validation.NewTestRuleResolver(tt.roles, tt.roleBindings, tt.clusterRoles, tt.clusterRoleBindings)
 		a := RBACAuthorizer{tt.superUser, ruleResolver}
 		for _, attr := range tt.shouldPass {
-			if err := a.Authorize(attr); err != nil {
-				t.Errorf("case %d: incorrectly restricted %s: %T %v", i, attr, err, err)
+			if authorized, _, _ := a.Authorize(attr); !authorized {
+				t.Errorf("case %d: incorrectly restricted %s", i, attr)
 			}
 		}
 
 		for _, attr := range tt.shouldFail {
-			if err := a.Authorize(attr); err == nil {
+			if authorized, _, _ := a.Authorize(attr); authorized {
 				t.Errorf("case %d: incorrectly passed %s", i, attr)
 			}
 		}
diff --git a/plugin/pkg/auth/authorizer/webhook/webhook.go b/plugin/pkg/auth/authorizer/webhook/webhook.go
index 621c72ec9c235..1b4b463e2d427 100644
--- a/plugin/pkg/auth/authorizer/webhook/webhook.go
+++ b/plugin/pkg/auth/authorizer/webhook/webhook.go
@@ -19,7 +19,6 @@ package webhook
 
 import (
 	"encoding/json"
-	"errors"
 	"fmt"
 	"time"
 
@@ -128,7 +127,7 @@ func newWithBackoff(kubeConfigFile string, authorizedTTL, unauthorizedTTL, initi
 //       }
 //     }
 //
-func (w *WebhookAuthorizer) Authorize(attr authorizer.Attributes) (err error) {
+func (w *WebhookAuthorizer) Authorize(attr authorizer.Attributes) (authorized bool, reason string, err error) {
 	r := &v1beta1.SubjectAccessReview{}
 	if user := attr.GetUser(); user != nil {
 		r.Spec = v1beta1.SubjectAccessReviewSpec{
@@ -156,7 +155,7 @@ func (w *WebhookAuthorizer) Authorize(attr authorizer.Attributes) (err error) {
 	}
 	key, err := json.Marshal(r.Spec)
 	if err != nil {
-		return err
+		return false, "", err
 	}
 	if entry, ok := w.responseCache.Get(string(key)); ok {
 		r.Status = entry.(v1beta1.SubjectAccessReviewStatus)
@@ -167,14 +166,17 @@ func (w *WebhookAuthorizer) Authorize(attr authorizer.Attributes) (err error) {
 		if err := result.Error(); err != nil {
 			// An error here indicates bad configuration or an outage. Log for debugging.
 			glog.Errorf("Failed to make webhook authorizer request: %v", err)
-			return err
+			return false, "", err
 		}
 		var statusCode int
-		if result.StatusCode(&statusCode); statusCode < 200 || statusCode >= 300 {
-			return fmt.Errorf("Error contacting webhook: %d", statusCode)
+		result.StatusCode(&statusCode)
+		switch {
+		case statusCode < 200,
+			statusCode >= 300:
+			return false, "", fmt.Errorf("Error contacting webhook: %d", statusCode)
 		}
 		if err := result.Into(r); err != nil {
-			return err
+			return false, "", err
 		}
 		if r.Status.Allowed {
 			w.responseCache.Add(string(key), r.Status, w.authorizedTTL)
@@ -182,11 +184,5 @@ func (w *WebhookAuthorizer) Authorize(attr authorizer.Attributes) (err error) {
 			w.responseCache.Add(string(key), r.Status, w.unauthorizedTTL)
 		}
 	}
-	if r.Status.Allowed {
-		return nil
-	}
-	if r.Status.Reason != "" {
-		return errors.New(r.Status.Reason)
-	}
-	return errors.New("unauthorized")
+	return r.Status.Allowed, r.Status.Reason, nil
 }
diff --git a/plugin/pkg/auth/authorizer/webhook/webhook_test.go b/plugin/pkg/auth/authorizer/webhook/webhook_test.go
index 7210287dfe3a0..613e3db2dc0ef 100644
--- a/plugin/pkg/auth/authorizer/webhook/webhook_test.go
+++ b/plugin/pkg/auth/authorizer/webhook/webhook_test.go
@@ -299,22 +299,25 @@ func TestTLSConfig(t *testing.T) {
 		test                            string
 		clientCert, clientKey, clientCA []byte
 		serverCert, serverKey, serverCA []byte
-		wantErr                         bool
+		wantAuth, wantErr               bool
 	}{
 		{
 			test:       "TLS setup between client and server",
 			clientCert: clientCert, clientKey: clientKey, clientCA: caCert,
 			serverCert: serverCert, serverKey: serverKey, serverCA: caCert,
+			wantAuth: true,
 		},
 		{
 			test:       "Server does not require client auth",
 			clientCA:   caCert,
 			serverCert: serverCert, serverKey: serverKey,
+			wantAuth: true,
 		},
 		{
 			test:       "Server does not require client auth, client provides it",
 			clientCert: clientCert, clientKey: clientKey, clientCA: caCert,
 			serverCert: serverCert, serverKey: serverKey,
+			wantAuth: true,
 		},
 		{
 			test:       "Client does not trust server",
@@ -357,7 +360,16 @@ func TestTLSConfig(t *testing.T) {
 
 			// Allow all and see if we get an error.
 			service.Allow()
-			err = wh.Authorize(attr)
+			authorized, _, err := wh.Authorize(attr)
+			if tt.wantAuth {
+				if !authorized {
+					t.Errorf("expected successful authorization")
+				}
+			} else {
+				if authorized {
+					t.Errorf("expected failed authorization")
+				}
+			}
 			if tt.wantErr {
 				if err == nil {
 					t.Errorf("expected error making authorization request: %v", err)
@@ -370,7 +382,7 @@ func TestTLSConfig(t *testing.T) {
 			}
 
 			service.Deny()
-			if err := wh.Authorize(attr); err == nil {
+			if authorized, _, _ := wh.Authorize(attr); authorized {
 				t.Errorf("%s: incorrectly authorized with DenyAll policy", tt.test)
 			}
 		}()
@@ -473,8 +485,12 @@ func TestWebhook(t *testing.T) {
 	}
 
 	for i, tt := range tests {
-		if err := wh.Authorize(tt.attr); err != nil {
-			t.Errorf("case %d: authorization failed: %v", i, err)
+		authorized, _, err := wh.Authorize(tt.attr)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if !authorized {
+			t.Errorf("case %d: authorization failed", i)
 			continue
 		}
 
@@ -489,6 +505,34 @@ func TestWebhook(t *testing.T) {
 	}
 }
 
+type webhookCacheTestCase struct {
+	statusCode         int
+	expectedErr        bool
+	expectedAuthorized bool
+	expectedCached     bool
+}
+
+func testWebhookCacheCases(t *testing.T, serv *mockService, wh *WebhookAuthorizer, attr authorizer.AttributesRecord, tests []webhookCacheTestCase) {
+	for _, test := range tests {
+		serv.statusCode = test.statusCode
+		authorized, _, err := wh.Authorize(attr)
+		if test.expectedErr && err == nil {
+			t.Errorf("Expected error")
+		} else if !test.expectedErr && err != nil {
+			t.Fatal(err)
+		}
+		if test.expectedAuthorized && !authorized {
+			if test.expectedCached {
+				t.Errorf("Webhook should have successful response cached, but authorizer reported unauthorized.")
+			} else {
+				t.Errorf("Webhook returned HTTP %d, but authorizer reported unauthorized.", test.statusCode)
+			}
+		} else if !test.expectedAuthorized && authorized {
+			t.Errorf("Webhook returned HTTP %d, but authorizer reported success.", test.statusCode)
+		}
+	}
+}
+
 // TestWebhookCache verifies that error responses from the server are not
 // cached, but successful responses are.
 func TestWebhookCache(t *testing.T) {
@@ -505,36 +549,27 @@ func TestWebhookCache(t *testing.T) {
 		t.Fatal(err)
 	}
 
+	tests := []webhookCacheTestCase{
+		{statusCode: 500, expectedErr: true, expectedAuthorized: false, expectedCached: false},
+		{statusCode: 404, expectedErr: true, expectedAuthorized: false, expectedCached: false},
+		{statusCode: 403, expectedErr: true, expectedAuthorized: false, expectedCached: false},
+		{statusCode: 401, expectedErr: true, expectedAuthorized: false, expectedCached: false},
+		{statusCode: 200, expectedErr: false, expectedAuthorized: true, expectedCached: false},
+		{statusCode: 500, expectedErr: false, expectedAuthorized: true, expectedCached: true},
+	}
+
 	attr := authorizer.AttributesRecord{User: &user.DefaultInfo{Name: "alice"}}
 	serv.allow = true
-	serv.statusCode = 500
-	if err := wh.Authorize(attr); err == nil {
-		t.Errorf("Webhook returned HTTP 500, but authorizer reported success.")
-	}
-	serv.statusCode = 404
-	if err := wh.Authorize(attr); err == nil {
-		t.Errorf("Webhook returned HTTP 404, but authorizer reported success.")
-	}
-	serv.statusCode = 200
-	if err := wh.Authorize(attr); err != nil {
-		t.Errorf("Webhook returned HTTP 200, but authorizer reported unauthorized.")
-	}
-	serv.statusCode = 500
-	if err := wh.Authorize(attr); err != nil {
-		t.Errorf("Webhook should have successful response cached, but authorizer reported unauthorized.")
-	}
+
+	testWebhookCacheCases(t, serv, wh, attr, tests)
+
 	// For a different request, webhook should be called again.
-	attr = authorizer.AttributesRecord{User: &user.DefaultInfo{Name: "bob"}}
-	serv.statusCode = 500
-	if err := wh.Authorize(attr); err == nil {
-		t.Errorf("Webhook returned HTTP 500, but authorizer reported success.")
-	}
-	serv.statusCode = 200
-	if err := wh.Authorize(attr); err != nil {
-		t.Errorf("Webhook returned HTTP 200, but authorizer reported unauthorized.")
-	}
-	serv.statusCode = 500
-	if err := wh.Authorize(attr); err != nil {
-		t.Errorf("Webhook should have successful response cached, but authorizer reported unauthorized.")
+	tests = []webhookCacheTestCase{
+		{statusCode: 500, expectedErr: true, expectedAuthorized: false, expectedCached: false},
+		{statusCode: 200, expectedErr: false, expectedAuthorized: true, expectedCached: false},
+		{statusCode: 500, expectedErr: false, expectedAuthorized: true, expectedCached: true},
 	}
+	attr = authorizer.AttributesRecord{User: &user.DefaultInfo{Name: "bob"}}
+
+	testWebhookCacheCases(t, serv, wh, attr, tests)
 }
diff --git a/test/integration/auth/auth_test.go b/test/integration/auth/auth_test.go
index d0e23fc2ad5f7..4370becd0cbca 100644
--- a/test/integration/auth/auth_test.go
+++ b/test/integration/auth/auth_test.go
@@ -25,7 +25,6 @@ package auth
 import (
 	"bytes"
 	"encoding/json"
-	"errors"
 	"fmt"
 	"io/ioutil"
 	"net/http"
@@ -536,11 +535,11 @@ func TestAuthModeAlwaysDeny(t *testing.T) {
 // TODO(etune): remove this test once a more comprehensive built-in authorizer is implemented.
 type allowAliceAuthorizer struct{}
 
-func (allowAliceAuthorizer) Authorize(a authorizer.Attributes) error {
+func (allowAliceAuthorizer) Authorize(a authorizer.Attributes) (bool, string, error) {
 	if a.GetUser() != nil && a.GetUser().GetName() == "alice" {
-		return nil
+		return true, "", nil
 	}
-	return errors.New("I can't allow that.  Go ask alice.")
+	return false, "I can't allow that.  Go ask alice.", nil
 }
 
 // TestAliceNotForbiddenOrUnauthorized tests a user who is known to
@@ -703,24 +702,24 @@ func TestUnknownUserIsUnauthorized(t *testing.T) {
 type impersonateAuthorizer struct{}
 
 // alice can't act as anyone and bob can't do anything but act-as someone
-func (impersonateAuthorizer) Authorize(a authorizer.Attributes) error {
+func (impersonateAuthorizer) Authorize(a authorizer.Attributes) (bool, string, error) {
 	// alice can impersonate service accounts and do other actions
 	if a.GetUser() != nil && a.GetUser().GetName() == "alice" && a.GetVerb() == "impersonate" && a.GetResource() == "serviceaccounts" {
-		return nil
+		return true, "", nil
 	}
 	if a.GetUser() != nil && a.GetUser().GetName() == "alice" && a.GetVerb() != "impersonate" {
-		return nil
+		return true, "", nil
 	}
 	// bob can impersonate anyone, but that it
 	if a.GetUser() != nil && a.GetUser().GetName() == "bob" && a.GetVerb() == "impersonate" {
-		return nil
+		return true, "", nil
 	}
 	// service accounts can do everything
 	if a.GetUser() != nil && strings.HasPrefix(a.GetUser().GetName(), serviceaccount.ServiceAccountUsernamePrefix) {
-		return nil
+		return true, "", nil
 	}
 
-	return errors.New("I can't allow that.  Go ask alice.")
+	return false, "I can't allow that.  Go ask alice.", nil
 }
 
 func TestImpersonateIsForbidden(t *testing.T) {
@@ -862,9 +861,9 @@ type trackingAuthorizer struct {
 	requestAttributes []authorizer.Attributes
 }
 
-func (a *trackingAuthorizer) Authorize(attributes authorizer.Attributes) error {
+func (a *trackingAuthorizer) Authorize(attributes authorizer.Attributes) (bool, string, error) {
 	a.requestAttributes = append(a.requestAttributes, attributes)
-	return nil
+	return true, "", nil
 }
 
 // TestAuthorizationAttributeDetermination tests that authorization attributes are built correctly
diff --git a/test/integration/serviceaccount/service_account_test.go b/test/integration/serviceaccount/service_account_test.go
index f6a38824c0a64..553f40438c2ee 100644
--- a/test/integration/serviceaccount/service_account_test.go
+++ b/test/integration/serviceaccount/service_account_test.go
@@ -369,7 +369,7 @@ func startServiceAccountTestServer(t *testing.T) (*clientset.Clientset, restclie
 	// 1. The "root" user is allowed to do anything
 	// 2. ServiceAccounts named "ro" are allowed read-only operations in their namespace
 	// 3. ServiceAccounts named "rw" are allowed any operation in their namespace
-	authorizer := authorizer.AuthorizerFunc(func(attrs authorizer.Attributes) error {
+	authorizer := authorizer.AuthorizerFunc(func(attrs authorizer.Attributes) (bool, string, error) {
 		username := ""
 		if user := attrs.GetUser(); user != nil {
 			username = user.GetName()
@@ -379,7 +379,7 @@ func startServiceAccountTestServer(t *testing.T) (*clientset.Clientset, restclie
 		// If the user is "root"...
 		if username == rootUserName {
 			// allow them to do anything
-			return nil
+			return true, "", nil
 		}
 
 		// If the user is a service account...
@@ -389,15 +389,15 @@ func startServiceAccountTestServer(t *testing.T) (*clientset.Clientset, restclie
 				switch serviceAccountName {
 				case readOnlyServiceAccountName:
 					if attrs.IsReadOnly() {
-						return nil
+						return true, "", nil
 					}
 				case readWriteServiceAccountName:
-					return nil
+					return true, "", nil
 				}
 			}
 		}
 
-		return fmt.Errorf("User %s is denied (ns=%s, readonly=%v, resource=%s)", username, ns, attrs.IsReadOnly(), attrs.GetResource())
+		return false, fmt.Sprintf("User %s is denied (ns=%s, readonly=%v, resource=%s)", username, ns, attrs.IsReadOnly(), attrs.GetResource()), nil
 	})
 
 	// Set up admission plugin to auto-assign serviceaccounts to pods