diff --git a/quic/core/quic_connection.cc b/quic/core/quic_connection.cc
index 05b5d88..bd745fd 100644
--- a/quic/core/quic_connection.cc
+++ b/quic/core/quic_connection.cc
@@ -6844,8 +6844,7 @@
 
 QuicConnectionId QuicConnection::GetOneActiveServerConnectionId() const {
   if (perspective_ == Perspective::IS_CLIENT ||
-      self_issued_cid_manager_ == nullptr ||
-      !use_active_cid_for_session_lookup_) {
+      self_issued_cid_manager_ == nullptr) {
     return connection_id();
   }
   auto active_connection_ids = GetActiveServerConnectionIds();
diff --git a/quic/core/quic_connection.h b/quic/core/quic_connection.h
index f05d2e0..eaec4cd 100644
--- a/quic/core/quic_connection.h
+++ b/quic/core/quic_connection.h
@@ -1246,10 +1246,6 @@
     return connection_migration_use_new_cid_;
   }
 
-  bool use_active_cid_for_session_lookup() const {
-    return use_active_cid_for_session_lookup_;
-  }
-
   bool count_bytes_on_alternative_path_separately() const {
     return count_bytes_on_alternative_path_separately_;
   }
@@ -2286,9 +2282,6 @@
 
   const bool add_missing_update_ack_timeout_ =
       GetQuicReloadableFlag(quic_add_missing_update_ack_timeout);
-
-  const bool use_active_cid_for_session_lookup_ =
-      GetQuicReloadableFlag(quic_use_active_cid_for_session_lookup);
 };
 
 }  // namespace quic
diff --git a/quic/core/quic_connection_test.cc b/quic/core/quic_connection_test.cc
index 64a8402..85c0abd 100644
--- a/quic/core/quic_connection_test.cc
+++ b/quic/core/quic_connection_test.cc
@@ -14944,25 +14944,17 @@
   // connection ID.
   connection_.ProcessUdpPacket(kSelfAddress, kPeerAddress, *packet1);
   EXPECT_EQ(connection_.connection_id(), cid0);
-  if (connection_.use_active_cid_for_session_lookup()) {
-    EXPECT_TRUE(connection_.GetOneActiveServerConnectionId() == cid0 ||
-                connection_.GetOneActiveServerConnectionId() == cid1 ||
-                connection_.GetOneActiveServerConnectionId() == cid2);
-  } else {
-    EXPECT_EQ(connection_.GetOneActiveServerConnectionId(), cid0);
-  }
+  EXPECT_TRUE(connection_.GetOneActiveServerConnectionId() == cid0 ||
+              connection_.GetOneActiveServerConnectionId() == cid1 ||
+              connection_.GetOneActiveServerConnectionId() == cid2);
 
   // cid0 is retired when the retire CID alarm fires.
   EXPECT_CALL(visitor_, OnServerConnectionIdRetired(cid0));
   retire_self_issued_cid_alarm->Fire();
   EXPECT_THAT(connection_.GetActiveServerConnectionIds(),
               ElementsAre(cid1, cid2));
-  if (connection_.use_active_cid_for_session_lookup()) {
-    EXPECT_TRUE(connection_.GetOneActiveServerConnectionId() == cid1 ||
-                connection_.GetOneActiveServerConnectionId() == cid2);
-  } else {
-    EXPECT_EQ(connection_.GetOneActiveServerConnectionId(), cid0);
-  }
+  EXPECT_TRUE(connection_.GetOneActiveServerConnectionId() == cid1 ||
+              connection_.GetOneActiveServerConnectionId() == cid2);
 
   // Packet3 updates the connection ID on the default path.
   connection_.ProcessUdpPacket(kSelfAddress, kPeerAddress, *packet3);
diff --git a/quic/core/quic_flags_list.h b/quic/core/quic_flags_list.h
index c9c9bdf..6f0617c 100644
--- a/quic/core/quic_flags_list.h
+++ b/quic/core/quic_flags_list.h
@@ -77,8 +77,6 @@
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_ignore_peer_max_ack_delay_during_handshake, true)
 // If true, include stream information in idle timeout connection close detail.
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_add_stream_info_to_idle_close_detail, true)
-// If true, looks up session to close via connection ID managed by self_issued_connection_id_manager instead of the one on default path.
-QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_use_active_cid_for_session_lookup, true)
 // If true, pass the received PATH_RESPONSE payload to path validator to move forward the path validation.
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_pass_path_response_to_validator, true)
 // If true, quic dispatcher supports one connection to use multiple connection IDs.