diff --git a/src/main/java/com/williamcallahan/javachat/adapters/out/clerk/ClerkApiKeyVerifier.java b/src/main/java/com/williamcallahan/javachat/adapters/out/clerk/ClerkApiKeyVerifier.java
index 2b3f9695..19ee24db 100644
--- a/src/main/java/com/williamcallahan/javachat/adapters/out/clerk/ClerkApiKeyVerifier.java
+++ b/src/main/java/com/williamcallahan/javachat/adapters/out/clerk/ClerkApiKeyVerifier.java
@@ -196,6 +196,12 @@ public Optional<VerifiedApiKey> verify(String presentedSecret) {
         if (verification.revoked() || verification.expired()) {
             return Optional.empty();
         }
+        if (verification.id() == null
+                || verification.id().isBlank()
+                || verification.subject() == null
+                || verification.subject().isBlank()) {
+            throw new ApiKeyOperationUnavailableException("Clerk returned an incomplete API key identity");
+        }
         VerifiedApiKey verifiedApiKey = new VerifiedApiKey(verification.id(), verification.subject());
         return Optional.of(verifiedApiKey);
     }
diff --git a/src/test/java/com/williamcallahan/javachat/adapters/out/clerk/ClerkApiKeyVerifierTest.java b/src/test/java/com/williamcallahan/javachat/adapters/out/clerk/ClerkApiKeyVerifierTest.java
index eb6d2f0b..635fd5ef 100644
--- a/src/test/java/com/williamcallahan/javachat/adapters/out/clerk/ClerkApiKeyVerifierTest.java
+++ b/src/test/java/com/williamcallahan/javachat/adapters/out/clerk/ClerkApiKeyVerifierTest.java
@@ -16,9 +16,11 @@
 import com.williamcallahan.javachat.application.auth.ApiKeyOperationUnavailableException;
 import com.williamcallahan.javachat.application.auth.VerifiedApiKey;
 import java.util.Optional;
+import java.util.stream.Stream;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.CsvSource;
+import org.junit.jupiter.params.provider.MethodSource;
 import org.springframework.http.HttpMethod;
 import org.springframework.http.MediaType;
 import org.springframework.test.web.client.MockRestServiceServer;
@@ -106,6 +108,30 @@ void rejectsIncompleteLifecycleState() {
         clerkServer.verify();
     }
 
+    @ParameterizedTest
+    @MethodSource("incompleteIdentityVerificationResponses")
+    void rejectsIncompleteIdentity(String verificationResponse) {
+        RestClient.Builder restClientBuilder = RestClient.builder();
+        MockRestServiceServer clerkServer =
+                MockRestServiceServer.bindTo(restClientBuilder).build();
+        ClerkApiKeyVerifier verifier = new ClerkApiKeyVerifier(restClientBuilder.build(), CLERK_SECRET_KEY);
+        clerkServer
+                .expect(requestTo(CLERK_VERIFY_ENDPOINT))
+                .andRespond(withSuccess(verificationResponse, MediaType.APPLICATION_JSON));
+
+        assertThrows(ApiKeyOperationUnavailableException.class, () -> verifier.verify(PRESENTED_API_KEY));
+        clerkServer.verify();
+    }
+
+    private static Stream<String> incompleteIdentityVerificationResponses() {
+        return Stream.of(
+                "{\"id\":\"ak_0123456789abcdef0123456789abcdef\",\"revoked\":false,\"expired\":false}",
+                "{\"subject\":\"user_0123456789abcdefghijklmnopq\",\"revoked\":false,\"expired\":false}",
+                "{\"revoked\":false,\"expired\":false}",
+                "{\"id\":\"ak_0123456789abcdef0123456789abcdef\",\"subject\":\"\",\"revoked\":false,\"expired\":false}",
+                "{\"id\":\"\",\"subject\":\"user_0123456789abcdefghijklmnopq\",\"revoked\":false,\"expired\":false}");
+    }
+
     @Test
     void distinguishesRejectedCredentialFromUnavailableVerification() {
         RestClient.Builder rejectionClientBuilder = RestClient.builder();
diff --git a/src/test/java/com/williamcallahan/javachat/web/AuthenticatedUserEndpointSecurityIntegrationTest.java b/src/test/java/com/williamcallahan/javachat/web/AuthenticatedUserEndpointSecurityIntegrationTest.java
index e9eedf5c..c89231c4 100644
--- a/src/test/java/com/williamcallahan/javachat/web/AuthenticatedUserEndpointSecurityIntegrationTest.java
+++ b/src/test/java/com/williamcallahan/javachat/web/AuthenticatedUserEndpointSecurityIntegrationTest.java
@@ -14,6 +14,7 @@
 import ch.qos.logback.classic.Level;
 import ch.qos.logback.classic.Logger;
 import ch.qos.logback.classic.spi.ILoggingEvent;
+import com.williamcallahan.javachat.adapters.in.web.security.ClerkApiKeyAuthenticationFilter;
 import com.williamcallahan.javachat.adapters.out.clerk.ClerkApiKeyVerifier;
 import com.williamcallahan.javachat.application.auth.ApiKeyOperationUnavailableException;
 import com.williamcallahan.javachat.application.auth.VerifiedApiKey;
@@ -173,6 +174,31 @@ void unavailableApiKeyRevocationReturns503AndLogsOneFailure() throws Exception {
         }
     }
 
+    @Test
+    void unavailableApiKeyVerificationReturns503AndLogsOneFailure() throws Exception {
+        ApiKeyOperationUnavailableException verificationFailure =
+                new ApiKeyOperationUnavailableException("Clerk returned an incomplete API key identity");
+        when(clerkApiKeyVerifier.verify(CLERK_API_KEY_SECRET)).thenThrow(verificationFailure);
+        Logger filterLogger = (Logger) LoggerFactory.getLogger(ClerkApiKeyAuthenticationFilter.class);
+
+        try (ExpectedLogEvents verificationLogEvents = ExpectedLogEvents.capture(filterLogger)) {
+            mockMvc.perform(get("/api/me").header("Authorization", "Bearer " + CLERK_API_KEY_SECRET))
+                    .andExpect(status().isServiceUnavailable())
+                    .andExpect(jsonPath("$.status").value("error"))
+                    .andExpect(jsonPath("$.message")
+                            .value("API key verification is temporarily unavailable. Please retry."));
+
+            assertEquals(1, verificationLogEvents.events().size());
+            ILoggingEvent verificationLogEvent = verificationLogEvents.events().getFirst();
+            assertEquals(Level.ERROR, verificationLogEvent.getLevel());
+            assertEquals("Clerk API key verification was unavailable", verificationLogEvent.getFormattedMessage());
+            assertEquals(
+                    ApiKeyOperationUnavailableException.class.getName(),
+                    verificationLogEvent.getThrowableProxy().getClassName());
+            assertFalse(verificationLogEvent.getFormattedMessage().contains(CLERK_API_KEY_SECRET));
+        }
+    }
+
     @Test
     void publicChatSurfaceStaysAnonymous() throws Exception {
         mockMvc.perform(get("/api/security/csrf")).andExpect(status().isOk());