diff --git a/attestation-service/src/bin/grpc/mod.rs b/attestation-service/src/bin/grpc/mod.rs
index faba652bc..c02d24d39 100644
--- a/attestation-service/src/bin/grpc/mod.rs
+++ b/attestation-service/src/bin/grpc/mod.rs
@@ -173,11 +173,6 @@ impl AttestationService for Arc<RwLock<AttestationServer>> {
             }
         };
 
-        let policy_ids = match request.policy_ids.is_empty() {
-            true => vec!["default".into()],
-            false => request.policy_ids,
-        };
-
         let attestation_token = self
             .read()
             .await
@@ -189,7 +184,7 @@ impl AttestationService for Arc<RwLock<AttestationServer>> {
                 runtime_data_hash_algorithm,
                 init_data,
                 init_data_hash_algorithm,
-                policy_ids,
+                request.policy_id,
             )
             .await
             .map_err(|e| Status::aborted(format!("Attestation: {e:?}")))?;
diff --git a/attestation-service/src/bin/restful/mod.rs b/attestation-service/src/bin/restful/mod.rs
index be0ee21a4..ec40beb3b 100644
--- a/attestation-service/src/bin/restful/mod.rs
+++ b/attestation-service/src/bin/restful/mod.rs
@@ -41,7 +41,7 @@ pub struct AttestationRequest {
     init_data: Option<Data>,
     runtime_data_hash_algorithm: Option<String>,
     init_data_hash_algorithm: Option<String>,
-    policy_ids: Vec<String>,
+    policy_id: String,
 }
 
 #[derive(Debug, Serialize, Deserialize)]
@@ -139,13 +139,6 @@ pub async fn attestation(
         }
     };
 
-    let policy_ids = if request.policy_ids.is_empty() {
-        info!("no policy specified, use `default`");
-        vec!["default".into()]
-    } else {
-        request.policy_ids
-    };
-
     let token = cocoas
         .read()
         .await
@@ -156,7 +149,7 @@ pub async fn attestation(
             runtime_data_hash_algorithm,
             init_data,
             init_data_hash_algorithm,
-            policy_ids,
+            request.policy_id,
         )
         .await
         .context("attestation report evaluate")?;
diff --git a/attestation-service/src/lib.rs b/attestation-service/src/lib.rs
index 466339c7c..abb4f4d10 100644
--- a/attestation-service/src/lib.rs
+++ b/attestation-service/src/lib.rs
@@ -175,7 +175,7 @@ impl AttestationService {
         runtime_data_hash_algorithm: HashAlgorithm,
         init_data: Option<Data>,
         init_data_hash_algorithm: HashAlgorithm,
-        policy_ids: Vec<String>,
+        policy_id: String,
     ) -> Result<String> {
         let verifier = verifier::to_verifier(&tee)?;
 
@@ -218,11 +218,7 @@ impl AttestationService {
 
         let appraisal = self
             .policy_engine
-            .evaluate(
-                reference_data_map.clone(),
-                tcb_claims,
-                policy_ids[0].clone(),
-            )
+            .evaluate(reference_data_map.clone(), tcb_claims, policy_id.clone())
             .await
             .map_err(|e| anyhow!("Policy Engine evaluation failed: {e}"))?;
 
diff --git a/attestation-service/tests/e2e/request.json.template b/attestation-service/tests/e2e/request.json.template
index b2218ee23..3bac75f1b 100644
--- a/attestation-service/tests/e2e/request.json.template
+++ b/attestation-service/tests/e2e/request.json.template
@@ -1,5 +1,5 @@
 {
     "tee": "%TEE_NAME%",
     "evidence": "%EVIDENCE%",
-    "policy_ids": []
-}
\ No newline at end of file
+    "policy_id": "default"
+}
diff --git a/kbs/src/attestation/coco/builtin.rs b/kbs/src/attestation/coco/builtin.rs
index cc0bdcf9d..b0f853474 100644
--- a/kbs/src/attestation/coco/builtin.rs
+++ b/kbs/src/attestation/coco/builtin.rs
@@ -40,7 +40,8 @@ impl Attest for BuiltInCoCoAs {
                 HashAlgorithm::Sha384,
                 None,
                 HashAlgorithm::Sha384,
-                vec!["default".into()],
+                // TODO: figure out a better way to set the policy id
+                "default",
             )
             .await
     }
diff --git a/kbs/src/attestation/coco/grpc.rs b/kbs/src/attestation/coco/grpc.rs
index 903dbf344..c21296459 100644
--- a/kbs/src/attestation/coco/grpc.rs
+++ b/kbs/src/attestation/coco/grpc.rs
@@ -110,7 +110,8 @@ impl Attest for GrpcClientPool {
             init_data_hash_algorithm: COCO_AS_HASH_ALGORITHM.into(),
             runtime_data: Some(RuntimeData::StructuredRuntimeData(runtime_data_plaintext)),
             init_data: None,
-            policy_ids: vec!["default".to_string()],
+            // TODO: figure out a better way to set this
+            policy_id: "default".to_string(),
         });
 
         let mut client = { self.pool.lock().await.get().await? };
diff --git a/protos/attestation.proto b/protos/attestation.proto
index 8e9b531b7..141cd530c 100644
--- a/protos/attestation.proto
+++ b/protos/attestation.proto
@@ -62,9 +62,8 @@ message AttestationRequest {
     // "sha384" or "sha512". If not specified, "sha384" will be selected.
     string init_data_hash_algorithm = 8;
 
-    // List of IDs of the policy used to check evidence. If not provided,
-    // a "default" one will be used.
-    repeated string policy_ids = 9;
+    // ID of the policy used to check evidence.
+    string policy_id = 9;
 }
 
 message AttestationResponse {