diff --git a/backend/src/app.ts b/backend/src/app.ts
index 477db2b54..053560320 100644
--- a/backend/src/app.ts
+++ b/backend/src/app.ts
@@ -3,7 +3,7 @@ import dotenv from "dotenv";
 import express from "express";
 import session from "express-session";
 
-import { getInitialDefences, getQALLMprePrompt } from "./defence";
+import { getInitialDefences } from "./defence";
 import { setOpenAiApiKey } from "./openai";
 import { router } from "./router";
 import { ChatCompletionRequestMessage } from "openai";
diff --git a/backend/src/defence.ts b/backend/src/defence.ts
index 2a6a99cfe..79ca0815f 100644
--- a/backend/src/defence.ts
+++ b/backend/src/defence.ts
@@ -230,8 +230,7 @@ function transformMessage(message: string, defences: DefenceInfo[]) {
 // detects triggered defences in original message and blocks the message if necessary
 async function detectTriggeredDefences(
   message: string,
-  defences: DefenceInfo[],
-  useLlmEvaluation: boolean
+  defences: DefenceInfo[]
 ) {
   // keep track of any triggered defences
   const defenceReport: ChatDefenceReport = {
@@ -263,18 +262,15 @@ async function detectTriggeredDefences(
   }
 
   // evaluate the message for prompt injection
-  // to speed up replies, only do this on phases where defences are active
-  if (useLlmEvaluation) {
-    const evalPrompt = await queryPromptEvaluationModel(message);
-    if (evalPrompt.isMalicious) {
-      defenceReport.triggeredDefences.push("LLM_EVALUATION");
-      if (isDefenceActive("LLM_EVALUATION", defences)) {
-        console.debug("LLM evalutation defence active.");
-        defenceReport.isBlocked = true;
-        defenceReport.blockedReason =
-          "Message blocked by the malicious prompt evaluator." +
-          evalPrompt.reason;
-      }
+  const evalPrompt = await queryPromptEvaluationModel(message);
+  if (evalPrompt.isMalicious) {
+    defenceReport.triggeredDefences.push("LLM_EVALUATION");
+    if (isDefenceActive("LLM_EVALUATION", defences)) {
+      console.debug("LLM evalutation defence active.");
+      defenceReport.isBlocked = true;
+      defenceReport.blockedReason =
+        "Message blocked by the malicious prompt evaluator." +
+        evalPrompt.reason;
     }
   }
 
diff --git a/backend/src/router.ts b/backend/src/router.ts
index 5d2700371..232a27105 100644
--- a/backend/src/router.ts
+++ b/backend/src/router.ts
@@ -130,18 +130,18 @@ router.post("/openai/chat", async (req, res) => {
     prevPhase = currentPhase;
     initQAModel(req.session.apiKey, retrievalQAPrePrompt, currentPhase);
   }
-
   if (message) {
     chatResponse.transformedMessage = message;
-    // see if this message triggers any defences
-    const useLlmEvaluation =
+    // see if this message triggers any defences (only for phase 2 and sandbox)
+    if (
       currentPhase === PHASE_NAMES.PHASE_2 ||
-      currentPhase === PHASE_NAMES.SANDBOX;
-    chatResponse.defenceInfo = await detectTriggeredDefences(
-      message,
-      req.session.defences,
-      useLlmEvaluation
-    );
+      currentPhase === PHASE_NAMES.SANDBOX
+    ) {
+      chatResponse.defenceInfo = await detectTriggeredDefences(
+        message,
+        req.session.defences
+      );
+    }
     // if blocked, send the response
     if (!chatResponse.defenceInfo.isBlocked) {
       // transform the message according to active defences
diff --git a/backend/test/unit/defence.test.ts b/backend/test/unit/defence.test.ts
index 3129d1b69..9bcdcc993 100644
--- a/backend/test/unit/defence.test.ts
+++ b/backend/test/unit/defence.test.ts
@@ -111,7 +111,7 @@ test("GIVEN XML_TAGGING defence is active WHEN transforming message THEN message
 test("GIVEN no defences are active WHEN detecting triggered defences THEN no defences are triggered", async () => {
   const message = "Hello";
   const defences = getInitialDefences();
-  const defenceReport = await detectTriggeredDefences(message, defences, false);
+  const defenceReport = await detectTriggeredDefences(message, defences);
   expect(defenceReport.blockedReason).toBe(null);
   expect(defenceReport.isBlocked).toBe(false);
   expect(defenceReport.triggeredDefences.length).toBe(0);
@@ -133,11 +133,7 @@ test(
         value: String(3),
       },
     ]);
-    const defenceReport = await detectTriggeredDefences(
-      message,
-      defences,
-      false
-    );
+    const defenceReport = await detectTriggeredDefences(message, defences);
     expect(defenceReport.blockedReason).toBe("Message is too long");
     expect(defenceReport.isBlocked).toBe(true);
     expect(defenceReport.triggeredDefences).toContain("CHARACTER_LIMIT");
@@ -160,11 +156,7 @@ test(
         value: String(280),
       },
     ]);
-    const defenceReport = await detectTriggeredDefences(
-      message,
-      defences,
-      false
-    );
+    const defenceReport = await detectTriggeredDefences(message, defences);
     expect(defenceReport.blockedReason).toBe(null);
     expect(defenceReport.isBlocked).toBe(false);
     expect(defenceReport.triggeredDefences.length).toBe(0);
@@ -185,11 +177,7 @@ test(
         value: String(3),
       },
     ]);
-    const defenceReport = await detectTriggeredDefences(
-      message,
-      defences,
-      false
-    );
+    const defenceReport = await detectTriggeredDefences(message, defences);
     expect(defenceReport.blockedReason).toBe(null);
     expect(defenceReport.isBlocked).toBe(false);
     expect(defenceReport.triggeredDefences).toContain("CHARACTER_LIMIT");
@@ -199,7 +187,7 @@ test(
 test("GIVEN message contains XML tags WHEN detecting triggered defences THEN XML_TAGGING defence is triggered", async () => {
   const message = "<Hello>";
   const defences = getInitialDefences();
-  const defenceReport = await detectTriggeredDefences(message, defences, false);
+  const defenceReport = await detectTriggeredDefences(message, defences);
   expect(defenceReport.blockedReason).toBe(null);
   expect(defenceReport.isBlocked).toBe(false);
   expect(defenceReport.triggeredDefences).toContain("XML_TAGGING");