diff --git a/adapter/BUILD b/adapter/BUILD
index 68a50d4..f42b913 100644
--- a/adapter/BUILD
+++ b/adapter/BUILD
@@ -11,6 +11,7 @@
         "apigeeReport.go",
         "applications.go",
         "products.go",
+        "rejecter.go",
     ],
     deps = [
         "//adapter/config:go_default_library",
@@ -27,6 +28,7 @@
         "apigeeKeyAttributes_test.go",
         "apigeeKeyChecker_test.go",
         "apigeeReport_test.go",
+        "rejecter_test.go",
     ],
     library = ":go_default_library",
     deps = [
diff --git a/adapter/apigee.go b/adapter/apigee.go
index a1f7b75..a35c438 100644
--- a/adapter/apigee.go
+++ b/adapter/apigee.go
@@ -25,6 +25,7 @@
 // aspect of the Apigee functionality.
 func Register(r adapter.Registrar) {
 	r.RegisterListsBuilder(newKeyCheckBuilder())
+	r.RegisterListsBuilder(newRejectBuilder())
 	//r.RegisterApplicationLogsBuilder(newReportBuilder())
 	r.RegisterAccessLogsBuilder(newReportBuilder())
 	r.RegisterAttributesGeneratorBuilder(newKeyAttrsBuilder())
diff --git a/adapter/apigeeKeyAttributes.go b/adapter/apigeeKeyAttributes.go
index db93ed5..6971f98 100644
--- a/adapter/apigeeKeyAttributes.go
+++ b/adapter/apigeeKeyAttributes.go
@@ -74,13 +74,18 @@
 }
 
 func (g *keyAttrsGenerator) Generate(in map[string]interface{}) (map[string]interface{}, error) {
+
+	out := make(map[string]interface{})
+	out[successParam] = false
+	out[successStringParam] = "false"
+
 	key := getString(in, keyParam)
 	if key == "" {
-		return nil, fmt.Errorf("Cannot verify API key: value of \"%s\" not found", keyParam)
+		return out, nil
 	}
 	path := getString(in, pathParam)
 	if path == "" {
-		return nil, fmt.Errorf("Cannot verify API key: value of \"%s\" not found", pathParam)
+		return out, nil
 	}
 
 	// Look up API key from cache, making HTTP request if necessary
@@ -102,7 +107,6 @@
 	}
 	// TODO match API products by path
 
-	out := make(map[string]interface{})
 	out[successParam] = success
 	out[successStringParam] = strconv.FormatBool(success)
 	if app.valid {
diff --git a/adapter/apigeeKeyAttributes_test.go b/adapter/apigeeKeyAttributes_test.go
index b2b5883..28d9438 100644
--- a/adapter/apigeeKeyAttributes_test.go
+++ b/adapter/apigeeKeyAttributes_test.go
@@ -23,6 +23,74 @@
 	"github.com/apid/istioApigeeAdapter/mock"
 )
 
+func TestMissingKey(t *testing.T) {
+	cfg := &config.VerifyKeyParams{
+		Organization:    "foo",
+		Environment:     "test",
+		VerificationURL: "http://" + mockServer.Address(),
+	}
+
+	builder := newKeyAttrsBuilder()
+	ce := builder.ValidateConfig(cfg)
+	if ce != nil {
+		t.Fatalf("Error validating config: %s", ce)
+	}
+
+	ag, err := builder.BuildAttributesGenerator(mockEnv, cfg)
+	if err != nil {
+		t.Fatalf("Error creating aspect: %s", err)
+	}
+	defer ag.Close()
+
+	in := make(map[string]interface{})
+
+	out, err := ag.Generate(in)
+	if err != nil {
+		t.Fatalf("Error checking parameters: %s", err)
+	}
+	if out[successParam] != false {
+		t.Fatal("Expected success to be false")
+	}
+	if out[successStringParam] != "false" {
+		t.Fatal("Expected success string to be false")
+	}
+}
+
+func TestEmptyKey(t *testing.T) {
+	cfg := &config.VerifyKeyParams{
+		Organization:    "foo",
+		Environment:     "test",
+		VerificationURL: "http://" + mockServer.Address(),
+	}
+
+	builder := newKeyAttrsBuilder()
+	ce := builder.ValidateConfig(cfg)
+	if ce != nil {
+		t.Fatalf("Error validating config: %s", ce)
+	}
+
+	ag, err := builder.BuildAttributesGenerator(mockEnv, cfg)
+	if err != nil {
+		t.Fatalf("Error creating aspect: %s", err)
+	}
+	defer ag.Close()
+
+	in := make(map[string]interface{})
+	in[keyParam] = "99999"
+	in[pathParam] = "/"
+
+	out, err := ag.Generate(in)
+	if err != nil {
+		t.Fatalf("Error checking parameters: %s", err)
+	}
+	if out[successParam] != false {
+		t.Fatal("Expected success to be false")
+	}
+	if out[successStringParam] != "false" {
+		t.Fatal("Expected success string to be false")
+	}
+}
+
 func TestInvalidKeyAttributes(t *testing.T) {
 	cfg := &config.VerifyKeyParams{
 		Organization:    "foo",
diff --git a/adapter/config/config.proto b/adapter/config/config.proto
index b069fbc..d51106b 100644
--- a/adapter/config/config.proto
+++ b/adapter/config/config.proto
@@ -29,6 +29,11 @@
   string verificationURL = 3;
 }
 
+message RejectParams {
+   // An optional error message to return
+  string message = 1;
+}
+
 message ReportParams {
   // The name of the Apigee organization -- required
   string organization = 1;
diff --git a/adapter/rejecter.go b/adapter/rejecter.go
new file mode 100644
index 0000000..f22c483
--- /dev/null
+++ b/adapter/rejecter.go
@@ -0,0 +1,66 @@
+/*
+Copyright 2017 Google Inc.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package adapter
+
+import (
+	"strconv"
+
+	"github.com/apid/istioApigeeAdapter/adapter/config"
+	"istio.io/mixer/pkg/adapter"
+)
+
+const (
+	rejectName = "rejecter"
+	rejectDesc = "Reject unless the expression is 'true'"
+)
+
+var rejectConf = &config.RejectParams{}
+
+type rejectBuilder struct {
+	adapter.DefaultBuilder
+}
+
+type rejecter struct {
+	message string
+}
+
+func newRejectBuilder() adapter.ListsBuilder {
+	return rejectBuilder{
+		adapter.NewDefaultBuilder(rejectName, rejectDesc, rejectConf),
+	}
+}
+
+func (b rejectBuilder) NewListsAspect(env adapter.Env, c adapter.Config) (adapter.ListsAspect, error) {
+	cfg := c.(*config.RejectParams)
+	r := &rejecter{
+		message: cfg.Message,
+	}
+	return r, nil
+}
+
+func (l *rejecter) Close() error {
+	return nil
+}
+
+func (l *rejecter) CheckList(symbol string) (bool, error) {
+	isTrue, err := strconv.ParseBool(symbol)
+	if err != nil {
+		// Error here means something like an empty string
+		return false, nil
+	}
+	return isTrue, nil
+}
diff --git a/adapter/rejecter_test.go b/adapter/rejecter_test.go
new file mode 100644
index 0000000..1c671cc
--- /dev/null
+++ b/adapter/rejecter_test.go
@@ -0,0 +1,89 @@
+/*
+Copyright 2017 Google Inc.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package adapter
+
+import (
+	"testing"
+
+	"github.com/apid/istioApigeeAdapter/adapter/config"
+)
+
+func TestRejectFalseness(t *testing.T) {
+	cfg := &config.RejectParams{}
+	builder := newRejectBuilder()
+	ce := builder.ValidateConfig(cfg)
+	if ce != nil {
+		t.Fatal("Config should validate")
+	}
+	aspect, err := builder.NewListsAspect(mockEnv, cfg)
+	if err != nil {
+		t.Fatalf("Error creating aspect: %s", err)
+	}
+	defer aspect.Close()
+
+	result, err := aspect.CheckList("false")
+	if err != nil {
+		t.Fatalf("Error on list check: %s", err)
+	}
+	if result {
+		t.Fatal("List check returned true and should have failed")
+	}
+}
+
+func TestRejectEmpty(t *testing.T) {
+	cfg := &config.RejectParams{}
+	builder := newRejectBuilder()
+	ce := builder.ValidateConfig(cfg)
+	if ce != nil {
+		t.Fatal("Config should validate")
+	}
+	aspect, err := builder.NewListsAspect(mockEnv, cfg)
+	if err != nil {
+		t.Fatalf("Error creating aspect: %s", err)
+	}
+	defer aspect.Close()
+
+	result, err := aspect.CheckList("")
+	if err != nil {
+		t.Fatalf("Error on list check: %s", err)
+	}
+	if result {
+		t.Fatal("List check returned true and should have failed")
+	}
+}
+
+func TestRejectTruthy(t *testing.T) {
+	cfg := &config.RejectParams{}
+	builder := newRejectBuilder()
+	ce := builder.ValidateConfig(cfg)
+	if ce != nil {
+		t.Fatal("Config should validate")
+	}
+	aspect, err := builder.NewListsAspect(mockEnv, cfg)
+	if err != nil {
+		t.Fatalf("Error creating aspect: %s", err)
+	}
+	defer aspect.Close()
+
+	result, err := aspect.CheckList("true")
+	if err != nil {
+		t.Fatalf("Error on list check: %s", err)
+	}
+	if !result {
+		t.Fatal("List check returned false")
+	}
+}