diff --git a/backend/src/defence.ts b/backend/src/defence.ts
index a8e2597cc..9359f72f6 100644
--- a/backend/src/defence.ts
+++ b/backend/src/defence.ts
@@ -45,14 +45,14 @@ const getInitialDefences = (): DefenceInfo[] => {
   ];
 };
 
-function activateDefence(id: string, defences: DefenceInfo[]) {
+function activateDefence(id: DEFENCE_TYPES, defences: DefenceInfo[]) {
   // return the updated list of defences
   return defences.map((defence) =>
     defence.id === id ? { ...defence, isActive: true } : defence
   );
 }
 
-function deactivateDefence(id: string, defences: DefenceInfo[]) {
+function deactivateDefence(id: DEFENCE_TYPES, defences: DefenceInfo[]) {
   // return the updated list of defences
   return defences.map((defence) =>
     defence.id === id ? { ...defence, isActive: false } : defence
@@ -60,7 +60,7 @@ function deactivateDefence(id: string, defences: DefenceInfo[]) {
 }
 
 function configureDefence(
-  id: string,
+  id: DEFENCE_TYPES,
   defences: DefenceInfo[],
   config: DefenceConfig[]
 ) {
@@ -72,7 +72,7 @@ function configureDefence(
 
 function getConfigValue(
   defences: DefenceInfo[],
-  defenceId: string,
+  defenceId: DEFENCE_TYPES,
   configId: string,
   defaultValue: string
 ) {
@@ -85,20 +85,20 @@ function getConfigValue(
 function getMaxMessageLength(defences: DefenceInfo[]) {
   return getConfigValue(
     defences,
-    "CHARACTER_LIMIT",
+    DEFENCE_TYPES.CHARACTER_LIMIT,
     "maxMessageLength",
     String(280)
   );
 }
 
 function getRandomSequenceEnclosurePrePrompt(defences: DefenceInfo[]) {
-  return getConfigValue(defences, "RANDOM_SEQUENCE_ENCLOSURE", "prePrompt", retrievalQAPrePromptSecure);
+  return getConfigValue(defences, DEFENCE_TYPES.RANDOM_SEQUENCE_ENCLOSURE, "prePrompt", retrievalQAPrePromptSecure);
 }
 
 function getRandomSequenceEnclosureLength(defences: DefenceInfo[]) {
   return getConfigValue(
     defences,
-    "RANDOM_SEQUENCE_ENCLOSURE",
+    DEFENCE_TYPES.RANDOM_SEQUENCE_ENCLOSURE,
     "length",
     String(10)
   );
@@ -117,19 +117,19 @@ function getSystemRole(
     case PHASE_NAMES.PHASE_2:
       return process.env.SYSTEM_ROLE_PHASE_2 || "";
     default:
-      return getConfigValue(defences, "SYSTEM_ROLE", "systemRole", "");
+      return getConfigValue(defences, DEFENCE_TYPES.SYSTEM_ROLE, "systemRole", "");
   }
 }
 
 function getEmailWhitelistVar(defences: DefenceInfo[]) {
-  return getConfigValue(defences, "EMAIL_WHITELIST", "whitelist", "");
+  return getConfigValue(defences, DEFENCE_TYPES.EMAIL_WHITELIST, "whitelist", "");
 }
 
 function getQALLMprePrompt(defences: DefenceInfo[]) {
-  return getConfigValue(defences, "QA_LLM_INSTRUCTIONS", "prePrompt", "");
+  return getConfigValue(defences, DEFENCE_TYPES.QA_LLM_INSTRUCTIONS, "prePrompt", "");
 }
 
-function isDefenceActive(id: string, defences: DefenceInfo[]) {
+function isDefenceActive(id: DEFENCE_TYPES, defences: DefenceInfo[]) {
   return defences.find((defence) => defence.id === id && defence.isActive)
     ? true
     : false;
@@ -207,13 +207,13 @@ function transformXmlTagging(message: string) {
 //apply defence string transformations to original message
 function transformMessage(message: string, defences: DefenceInfo[]) {
   let transformedMessage: string = message;
-  if (isDefenceActive("RANDOM_SEQUENCE_ENCLOSURE", defences)) {
+  if (isDefenceActive(DEFENCE_TYPES.RANDOM_SEQUENCE_ENCLOSURE, defences)) {
     transformedMessage = transformRandomSequenceEnclosure(
       transformedMessage,
       defences
     );
   }
-  if (isDefenceActive("XML_TAGGING", defences)) {
+  if (isDefenceActive(DEFENCE_TYPES.XML_TAGGING, defences)) {
     transformedMessage = transformXmlTagging(transformedMessage);
   }
   if (message == transformedMessage) {
@@ -242,9 +242,9 @@ async function detectTriggeredDefences(
   if (message.length > maxMessageLength) {
     console.debug("CHARACTER_LIMIT defence triggered.");
     // add the defence to the list of triggered defences
-    defenceReport.triggeredDefences.push("CHARACTER_LIMIT");
+    defenceReport.triggeredDefences.push(DEFENCE_TYPES.CHARACTER_LIMIT);
     // check if the defence is active
-    if (isDefenceActive("CHARACTER_LIMIT", defences)) {
+    if (isDefenceActive(DEFENCE_TYPES.CHARACTER_LIMIT, defences)) {
       // block the message
       defenceReport.isBlocked = true;
       defenceReport.blockedReason = "Message is too long";
@@ -257,14 +257,14 @@ async function detectTriggeredDefences(
   if (detectXMLTags(message)) {
     console.debug("XML_TAGGING defence triggered.");
     // add the defence to the list of triggered defences
-    defenceReport.triggeredDefences.push("XML_TAGGING");
+    defenceReport.triggeredDefences.push(DEFENCE_TYPES.XML_TAGGING);
   }
 
   // evaluate the message for prompt injection
   const evalPrompt = await queryPromptEvaluationModel(message);
   if (evalPrompt.isMalicious) {
-    defenceReport.triggeredDefences.push("LLM_EVALUATION");
-    if (isDefenceActive("LLM_EVALUATION", defences)) {
+    defenceReport.triggeredDefences.push(DEFENCE_TYPES.LLM_EVALUATION);
+    if (isDefenceActive(DEFENCE_TYPES.LLM_EVALUATION, defences)) {
       console.debug("LLM evalutation defence active.");
       defenceReport.isBlocked = true;
       defenceReport.blockedReason =
diff --git a/backend/src/email.ts b/backend/src/email.ts
index e60f4473c..7cad34ef5 100644
--- a/backend/src/email.ts
+++ b/backend/src/email.ts
@@ -1,4 +1,4 @@
-import { DefenceInfo } from "./models/defence";
+import { DEFENCE_TYPES, DefenceInfo } from "./models/defence";
 import { EmailInfo } from "./models/email";
 import { getEmailWhitelistVar, isDefenceActive } from "./defence";
 import { PHASE_NAMES } from "./models/phase";
@@ -11,7 +11,7 @@ function getEmailWhitelistValues(defences: DefenceInfo[]) {
 
 // if defense active return the whitelist of emails and domains
 function getEmailWhitelist(defences: DefenceInfo[]) {
-  if (!isDefenceActive("EMAIL_WHITELIST", defences)) {
+  if (!isDefenceActive(DEFENCE_TYPES.EMAIL_WHITELIST, defences)) {
     return "As the email whitelist defence is not active, any email address can be emailed.";
   } else {
     return (
diff --git a/backend/src/openai.ts b/backend/src/openai.ts
index bb0875d20..3da8401e3 100644
--- a/backend/src/openai.ts
+++ b/backend/src/openai.ts
@@ -13,7 +13,7 @@ import {
   OpenAIApi,
 } from "openai";
 import { CHAT_MODELS, ChatDefenceReport } from "./models/chat";
-import { DefenceInfo } from "./models/defence";
+import { DEFENCE_TYPES, DefenceInfo } from "./models/defence";
 import { PHASE_NAMES } from "./models/phase";
 
 // OpenAI config
@@ -165,8 +165,8 @@ async function chatGptCallFunction(
         isAllowedToSendEmail = true;
       } else {
         // trigger email defence even if it is not active
-        defenceInfo.triggeredDefences.push("EMAIL_WHITELIST");
-        if (isDefenceActive("EMAIL_WHITELIST", defences)) {
+        defenceInfo.triggeredDefences.push(DEFENCE_TYPES.EMAIL_WHITELIST);
+        if (isDefenceActive(DEFENCE_TYPES.EMAIL_WHITELIST, defences)) {
           // do not send email if defence is on and set to blocked
           defenceInfo.isBlocked = true;
           defenceInfo.blockedReason =
@@ -229,7 +229,7 @@ async function chatGptChatCompletion(
   // system role is always active on phases
   if (
     currentPhase !== PHASE_NAMES.SANDBOX ||
-    isDefenceActive("SYSTEM_ROLE", defences)
+    isDefenceActive(DEFENCE_TYPES.SYSTEM_ROLE, defences)
   ) {
     // check to see if there's already a system role
     if (!chatHistory.find((message) => message.role === "system")) {
diff --git a/backend/src/router.ts b/backend/src/router.ts
index ca641b149..70e139bdc 100644
--- a/backend/src/router.ts
+++ b/backend/src/router.ts
@@ -11,7 +11,7 @@ import {
 } from "./defence";
 import { initQAModel } from "./langchain";
 import { CHAT_MODELS, ChatHttpResponse } from "./models/chat";
-import { DefenceConfig } from "./models/defence";
+import { DEFENCE_TYPES, DefenceConfig } from "./models/defence";
 import { chatGptSendMessage, setOpenAiApiKey, setGptModel } from "./openai";
 import { retrievalQAPrePrompt } from "./promptTemplates";
 import { PHASE_NAMES } from "./models/phase";
@@ -24,13 +24,13 @@ let prevPhase: PHASE_NAMES = PHASE_NAMES.SANDBOX;
 // Activate a defence
 router.post("/defence/activate", (req, res) => {
   // id of the defence
-  const defenceId: string = req.body?.defenceId;
+  const defenceId: DEFENCE_TYPES = req.body?.defenceId;
   if (defenceId) {
     // activate the defence
     req.session.defences = activateDefence(defenceId, req.session.defences);
 
     // need to re-initialize QA model when turned on
-    if (defenceId === "QA_LLM_INSTRUCTIONS" && req.session.openAiApiKey) {
+    if (defenceId === DEFENCE_TYPES.QA_LLM_INSTRUCTIONS && req.session.openAiApiKey) {
       console.debug(
         "Activating qa llm instruction defence - reinitializing qa model"
       );
@@ -47,12 +47,12 @@ router.post("/defence/activate", (req, res) => {
 // Deactivate a defence
 router.post("/defence/deactivate", (req, res) => {
   // id of the defence
-  const defenceId: string = req.body?.defenceId;
+  const defenceId: DEFENCE_TYPES = req.body?.defenceId;
   if (defenceId) {
     // deactivate the defence
     req.session.defences = deactivateDefence(defenceId, req.session.defences);
 
-    if (defenceId === "QA_LLM_INSTRUCTIONS" && req.session.openAiApiKey) {
+    if (defenceId === DEFENCE_TYPES.QA_LLM_INSTRUCTIONS && req.session.openAiApiKey) {
       console.debug("Resetting QA model with default prompt");
       initQAModel(req.session.openAiApiKey, getQALLMprePrompt(req.session.defences));
     }
@@ -66,7 +66,7 @@ router.post("/defence/deactivate", (req, res) => {
 // Configure a defence
 router.post("/defence/configure", (req, res) => {
   // id of the defence
-  const defenceId: string = req.body?.defenceId;
+  const defenceId: DEFENCE_TYPES = req.body?.defenceId;
   const config: DefenceConfig[] = req.body?.config;
   if (defenceId && config) {
     // configure the defence
diff --git a/backend/test/integration/defences.test.ts b/backend/test/integration/defences.test.ts
index 350e4e943..910cdc363 100644
--- a/backend/test/integration/defences.test.ts
+++ b/backend/test/integration/defences.test.ts
@@ -1,5 +1,6 @@
 import { activateDefence, detectTriggeredDefences, getInitialDefences } from "../../src/defence";
 import { initPromptEvaluationModel } from "../../src/langchain";
+import { DEFENCE_TYPES } from "../../src/models/defence";
 
 // Define a mock implementation for the createChatCompletion method
 const mockCall = jest.fn();
@@ -31,14 +32,14 @@ test("GIVEN LLM_EVALUATION defence is active AND prompt is malicious WHEN detect
 
   let defences = getInitialDefences();
   // activate the defence
-  defences = activateDefence("LLM_EVALUATION", defences);
+  defences = activateDefence(DEFENCE_TYPES.LLM_EVALUATION, defences);
   // create a malicious prompt
   const message = "some kind of malicious prompt";
   // detect triggered defences
   const result = await detectTriggeredDefences(message, defences);
   // check that the defence is triggered and the message is blocked
   expect(result.isBlocked).toBe(true);
-  expect(result.triggeredDefences).toContain("LLM_EVALUATION");
+  expect(result.triggeredDefences).toContain(DEFENCE_TYPES.LLM_EVALUATION);
 });
 
 test("GIVEN LLM_EVALUATION defence is active AND prompt only triggers malice detection WHEN detectTriggeredDefences is called THEN defence is triggered AND defence is blocked", async () => {
@@ -53,14 +54,14 @@ test("GIVEN LLM_EVALUATION defence is active AND prompt only triggers malice det
 
   let defences = getInitialDefences();
   // activate the defence
-  defences = activateDefence("LLM_EVALUATION", defences);
+  defences = activateDefence(DEFENCE_TYPES.LLM_EVALUATION, defences);
   // create a malicious prompt
   const message = "some kind of malicious prompt";
   // detect triggered defences
   const result = await detectTriggeredDefences(message, defences);
   // check that the defence is triggered and the message is blocked
   expect(result.isBlocked).toBe(true);
-  expect(result.triggeredDefences).toContain("LLM_EVALUATION");
+  expect(result.triggeredDefences).toContain(DEFENCE_TYPES.LLM_EVALUATION);
 });
 
 test("GIVEN LLM_EVALUATION defence is active AND prompt only triggers prompt injection detection WHEN detectTriggeredDefences is called THEN defence is triggered AND defence is blocked", async () => {
@@ -75,14 +76,14 @@ test("GIVEN LLM_EVALUATION defence is active AND prompt only triggers prompt inj
 
   let defences = getInitialDefences();
   // activate the defence
-  defences = activateDefence("LLM_EVALUATION", defences);
+  defences = activateDefence(DEFENCE_TYPES.LLM_EVALUATION, defences);
   // create a malicious prompt
   const message = "some kind of malicious prompt";
   // detect triggered defences
   const result = await detectTriggeredDefences(message, defences);
   // check that the defence is triggered and the message is blocked
   expect(result.isBlocked).toBe(true);
-  expect(result.triggeredDefences).toContain("LLM_EVALUATION");
+  expect(result.triggeredDefences).toContain(DEFENCE_TYPES.LLM_EVALUATION);
 });
 
 test("GIVEN LLM_EVALUATION defence is active AND prompt not is malicious WHEN detectTriggeredDefences is called THEN defence is not triggered AND defence is not blocked", async () => {
@@ -97,7 +98,7 @@ test("GIVEN LLM_EVALUATION defence is active AND prompt not is malicious WHEN de
 
   let defences = getInitialDefences();
   // activate the defence
-  defences = activateDefence("LLM_EVALUATION", defences);
+  defences = activateDefence(DEFENCE_TYPES.LLM_EVALUATION, defences);
   // create a malicious prompt
   const message = "some kind of malicious prompt";
   // detect triggered defences
@@ -124,5 +125,5 @@ test("GIVEN LLM_EVALUATION defence is not active AND prompt is malicious WHEN de
   const result = await detectTriggeredDefences(message, defences);
   // check that the defence is triggered and the message is blocked
   expect(result.isBlocked).toBe(false);
-  expect(result.triggeredDefences).toContain("LLM_EVALUATION");
+  expect(result.triggeredDefences).toContain(DEFENCE_TYPES.LLM_EVALUATION);
 });
\ No newline at end of file
diff --git a/backend/test/integration/openai.test.ts b/backend/test/integration/openai.test.ts
index 096c193a7..62b3518b5 100644
--- a/backend/test/integration/openai.test.ts
+++ b/backend/test/integration/openai.test.ts
@@ -1,7 +1,7 @@
 import { ChatCompletionRequestMessage } from "openai";
 import { CHAT_MODELS } from "../../src/models/chat";
 import { chatGptSendMessage } from "../../src/openai";
-import { DefenceInfo } from "../../src/models/defence";
+import { DEFENCE_TYPES, DefenceInfo } from "../../src/models/defence";
 import { EmailInfo } from "../../src/models/email";
 import { activateDefence, getInitialDefences } from "../../src/defence";
 
@@ -91,7 +91,7 @@ test("GIVEN SYSTEM_ROLE defence is active WHEN sending message THEN system role
   const gptModel = CHAT_MODELS.GPT_4;
   const openAiApiKey = "sk-12345";
 
-  defences = activateDefence("SYSTEM_ROLE", defences);
+  defences = activateDefence(DEFENCE_TYPES.SYSTEM_ROLE, defences);
 
   // Mock the createChatCompletion function
   mockCreateChatCompletion.mockResolvedValueOnce({
@@ -154,7 +154,7 @@ test("GIVEN SYSTEM_ROLE defence is active WHEN sending message THEN system role
   const openAiApiKey = "sk-12345";
 
   // activate the SYSTEM_ROLE defence
-  defences = activateDefence("SYSTEM_ROLE", defences);
+  defences = activateDefence(DEFENCE_TYPES.SYSTEM_ROLE, defences);
 
   // Mock the createChatCompletion function
   mockCreateChatCompletion.mockResolvedValueOnce({
@@ -292,7 +292,7 @@ test(
     const gptModel = CHAT_MODELS.GPT_4;
     const openAiApiKey = "sk-12345";
 
-    defences = activateDefence("SYSTEM_ROLE", defences);
+    defences = activateDefence(DEFENCE_TYPES.SYSTEM_ROLE, defences);
 
     // Mock the createChatCompletion function
     mockCreateChatCompletion.mockResolvedValueOnce({
@@ -410,7 +410,7 @@ test(
     expect(reply?.defenceInfo.isBlocked).toBe(false);
     // EMAIL_WHITELIST defence is triggered
     expect(reply?.defenceInfo.triggeredDefences.length).toBe(1);
-    expect(reply?.defenceInfo.triggeredDefences[0]).toBe("EMAIL_WHITELIST");
+    expect(reply?.defenceInfo.triggeredDefences[0]).toBe(DEFENCE_TYPES.EMAIL_WHITELIST);
 
     // restore the mock
     mockCreateChatCompletion.mockRestore();
@@ -432,7 +432,7 @@ test(
     const gptModel = CHAT_MODELS.GPT_4;
     const openAiApiKey = "sk-12345";
 
-    defences = activateDefence("EMAIL_WHITELIST", defences);
+    defences = activateDefence(DEFENCE_TYPES.EMAIL_WHITELIST, defences);
 
     // Mock the createChatCompletion function
     mockCreateChatCompletion
@@ -486,7 +486,7 @@ test(
     expect(reply?.defenceInfo.isBlocked).toBe(true);
     // EMAIL_WHITELIST defence is triggered
     expect(reply?.defenceInfo.triggeredDefences.length).toBe(1);
-    expect(reply?.defenceInfo.triggeredDefences[0]).toBe("EMAIL_WHITELIST");
+    expect(reply?.defenceInfo.triggeredDefences[0]).toBe(DEFENCE_TYPES.EMAIL_WHITELIST);
 
     // restore the mock
     mockCreateChatCompletion.mockRestore();
@@ -508,7 +508,7 @@ test(
     const gptModel = CHAT_MODELS.GPT_4;
     const openAiApiKey = "sk-12345";
 
-    defences = activateDefence("EMAIL_WHITELIST", defences);
+    defences = activateDefence(DEFENCE_TYPES.EMAIL_WHITELIST, defences);
 
     // Mock the createChatCompletion function
     mockCreateChatCompletion
diff --git a/backend/test/unit/defence.test.ts b/backend/test/unit/defence.test.ts
index 23378508d..125234ee8 100644
--- a/backend/test/unit/defence.test.ts
+++ b/backend/test/unit/defence.test.ts
@@ -9,6 +9,7 @@ import {
   isDefenceActive,
   transformMessage,
 } from "../../src/defence";
+import { DEFENCE_TYPES } from "../../src/models/defence";
 import { PHASE_NAMES } from "../../src/models/phase";
 import { retrievalQAPrePromptSecure } from "../../src/promptTemplates";
 
@@ -18,21 +19,21 @@ beforeEach(() => {
 });
 
 test("GIVEN defence is not active WHEN activating defence THEN defence is active", () => {
-  const defence = "SYSTEM_ROLE";
+  const defence = DEFENCE_TYPES.SYSTEM_ROLE;
   const defences = getInitialDefences();
   const updatedActiveDefences = activateDefence(defence, defences);
   expect(isDefenceActive(defence, updatedActiveDefences)).toBe(true);
 });
 
 test("GIVEN defence is active WHEN activating defence THEN defence is active", () => {
-  const defence = "SYSTEM_ROLE";
+  const defence = DEFENCE_TYPES.SYSTEM_ROLE;
   const defences = getInitialDefences();
   const updatedActiveDefences = activateDefence(defence, defences);
   expect(isDefenceActive(defence, updatedActiveDefences)).toBe(true);
 });
 
 test("GIVEN defence is active WHEN deactivating defence THEN defence is not active", () => {
-  const defence = "SYSTEM_ROLE";
+  const defence = DEFENCE_TYPES.SYSTEM_ROLE;
   const defences = getInitialDefences();
   activateDefence(defence, defences);
   const updatedActiveDefences = deactivateDefence(defence, defences);
@@ -40,14 +41,14 @@ test("GIVEN defence is active WHEN deactivating defence THEN defence is not acti
 });
 
 test("GIVEN defence is not active WHEN deactivating defence THEN defence is not active", () => {
-  const defence = "SYSTEM_ROLE";
+  const defence = DEFENCE_TYPES.SYSTEM_ROLE;
   const defences = getInitialDefences();
   const updatedActiveDefences = deactivateDefence(defence, defences);
   expect(updatedActiveDefences).not.toContain(defence);
 });
 
 test("GIVEN defence is active WHEN checking if defence is active THEN return true", () => {
-  const defence = "SYSTEM_ROLE";
+  const defence = DEFENCE_TYPES.SYSTEM_ROLE;
   const defences = getInitialDefences();
   const updatedDefences = activateDefence(defence, defences);
   const isActive = isDefenceActive(defence, updatedDefences);
@@ -55,7 +56,7 @@ test("GIVEN defence is active WHEN checking if defence is active THEN return tru
 });
 
 test("GIVEN defence is not active WHEN checking if defence is active THEN return false", () => {
-  const defence = "SYSTEM_ROLE";
+  const defence = DEFENCE_TYPES.SYSTEM_ROLE;
   const defences = getInitialDefences();
   const isActive = isDefenceActive(defence, defences);
   expect(isActive).toBe(false);
@@ -77,7 +78,7 @@ test("GIVEN RANDOM_SEQUENCE_ENCLOSURE defence is active WHEN transforming messag
   const message = "Hello";
   let defences = getInitialDefences();
   // activate RSE defence
-  defences = activateDefence("RANDOM_SEQUENCE_ENCLOSURE", defences);
+  defences = activateDefence(DEFENCE_TYPES.RANDOM_SEQUENCE_ENCLOSURE, defences);
 
   // regex to match the transformed message with
   const regex = new RegExp(
@@ -110,7 +111,7 @@ test("GIVEN XML_TAGGING defence is active WHEN transforming message THEN message
   const message = "Hello";
   const defences = getInitialDefences();
   // activate XML_TAGGING defence
-  const updatedDefences = activateDefence("XML_TAGGING", defences);
+  const updatedDefences = activateDefence(DEFENCE_TYPES.XML_TAGGING, defences);
   const transformedMessage = transformMessage(message, updatedDefences);
   // expect the message to be surrounded by XML tags
   expect(transformedMessage).toBe("<user_input>" + message + "</user_input>");
@@ -121,7 +122,7 @@ test("GIVEN XML_TAGGING defence is active AND message contains XML tags WHEN tra
   const escapedMessage = "&lt;&gt;&amp;&apos;&quot;";
   const defences = getInitialDefences();
   // activate XML_TAGGING defence
-  const updatedDefences = activateDefence("XML_TAGGING", defences);
+  const updatedDefences = activateDefence(DEFENCE_TYPES.XML_TAGGING, defences);
   const transformedMessage = transformMessage(message, updatedDefences);
   // expect the message to be surrounded by XML tags
   expect(transformedMessage).toBe(
@@ -146,9 +147,9 @@ test(
     const message = "Hello";
     let defences = getInitialDefences();
     // activate CHARACTER_LIMIT defence
-    defences = activateDefence("CHARACTER_LIMIT", defences);
+    defences = activateDefence(DEFENCE_TYPES.CHARACTER_LIMIT, defences);
     // configure CHARACTER_LIMIT defence
-    defences = configureDefence("CHARACTER_LIMIT", defences, [
+    defences = configureDefence(DEFENCE_TYPES.CHARACTER_LIMIT, defences, [
       {
         id: "maxMessageLength",
         value: String(3),
@@ -157,7 +158,7 @@ test(
     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");
+    expect(defenceReport.triggeredDefences).toContain(DEFENCE_TYPES.CHARACTER_LIMIT);
   }
 );
 
@@ -169,9 +170,9 @@ test(
     const message = "Hello";
     const defences = getInitialDefences();
     // activate CHARACTER_LIMIT defence
-    activateDefence("CHARACTER_LIMIT", defences);
+    activateDefence(DEFENCE_TYPES.CHARACTER_LIMIT, defences);
     // configure CHARACTER_LIMIT defence
-    configureDefence("CHARACTER_LIMIT", defences, [
+    configureDefence(DEFENCE_TYPES.CHARACTER_LIMIT, defences, [
       {
         id: "maxMessageLength",
         value: String(280),
@@ -192,7 +193,7 @@ test(
     const message = "Hello";
     let defences = getInitialDefences();
     // configure CHARACTER_LIMIT defence
-    defences = configureDefence("CHARACTER_LIMIT", defences, [
+    defences = configureDefence(DEFENCE_TYPES.CHARACTER_LIMIT, defences, [
       {
         id: "maxMessageLength",
         value: String(3),
@@ -201,7 +202,7 @@ test(
     const defenceReport = await detectTriggeredDefences(message, defences);
     expect(defenceReport.blockedReason).toBe(null);
     expect(defenceReport.isBlocked).toBe(false);
-    expect(defenceReport.triggeredDefences).toContain("CHARACTER_LIMIT");
+    expect(defenceReport.triggeredDefences).toContain(DEFENCE_TYPES.CHARACTER_LIMIT);
   }
 );
 
@@ -211,11 +212,11 @@ test("GIVEN message contains XML tags WHEN detecting triggered defences THEN XML
   const defenceReport = await detectTriggeredDefences(message, defences);
   expect(defenceReport.blockedReason).toBe(null);
   expect(defenceReport.isBlocked).toBe(false);
-  expect(defenceReport.triggeredDefences).toContain("XML_TAGGING");
+  expect(defenceReport.triggeredDefences).toContain(DEFENCE_TYPES.XML_TAGGING);
 });
 
 test("GIVEN setting max message length WHEN configuring defence THEN defence is configured", () => {
-  const defence = "CHARACTER_LIMIT";
+  const defence = DEFENCE_TYPES.CHARACTER_LIMIT;
   let defences = getInitialDefences();
   // configure CHARACTER_LIMIT defence
   defences = configureDefence(defence, defences, [
@@ -257,7 +258,7 @@ test("GIVEN a new system role has been set WHEN getting system role THEN return
   let defences = getInitialDefences();
   let systemRole = getSystemRole(defences);
   expect(systemRole).toBe("system role");
-  defences = configureDefence("SYSTEM_ROLE", defences, [
+  defences = configureDefence(DEFENCE_TYPES.SYSTEM_ROLE, defences, [
     { id: "systemRole", value: "new system role" },
   ]);
   systemRole = getSystemRole(defences);
@@ -296,7 +297,7 @@ test("GIVEN QA LLM instructions have not been configured WHEN getting QA LLM ins
 test("GIVEN QA LLM instructions have been configured WHEN getting QA LLM instructions THEN return configured prompt", () => {
   const newQaLlmInstructions = "new QA LLM instructions";
   let defences = getInitialDefences();
-  defences = configureDefence("QA_LLM_INSTRUCTIONS", defences, [
+  defences = configureDefence(DEFENCE_TYPES.QA_LLM_INSTRUCTIONS, defences, [
     { id: "prePrompt", value: newQaLlmInstructions },
   ]);
   const qaLlmInstructions = getQALLMprePrompt(defences);
@@ -304,7 +305,7 @@ test("GIVEN QA LLM instructions have been configured WHEN getting QA LLM instruc
 });
 
 test("GIVEN setting email whitelist WHEN configuring defence THEN defence is configured", () => {
-  const defence = "EMAIL_WHITELIST";
+  const defence = DEFENCE_TYPES.EMAIL_WHITELIST;
   const defences = getInitialDefences();
   // configure EMAIL_WHITELIST defence
   configureDefence(defence, defences, [
@@ -331,7 +332,7 @@ test("GIVEN setting email whitelist WHEN configuring defence THEN defence is con
 });
 
 test("GIVEN user configures random sequence enclosure WHEN configuring defence THEN defence is configured", () => {
-  const defence = "RANDOM_SEQUENCE_ENCLOSURE";
+  const defence = DEFENCE_TYPES.RANDOM_SEQUENCE_ENCLOSURE;
   let defences = getInitialDefences();
   const newPrePrompt = "new pre prompt";
   const newLength = String(100);
diff --git a/backend/test/unit/email.test.ts b/backend/test/unit/email.test.ts
index 4598bb746..b04a686b2 100644
--- a/backend/test/unit/email.test.ts
+++ b/backend/test/unit/email.test.ts
@@ -4,6 +4,7 @@ import {
   isEmailInWhitelist,
   sendEmail,
 } from "../../src/email";
+import { DEFENCE_TYPES } from "../../src/models/defence";
 import { PHASE_NAMES } from "../../src/models/phase";
 
 beforeEach(() => {
@@ -153,7 +154,7 @@ test("GIVEN EMAIL_WHITELIST envionrment variable is set WHEN getting whitelist A
   process.env.EMAIL_WHITELIST = "bob@example.com,kate@example.com";
   let defences = getInitialDefences();
   // activate email whitelist defence
-  defences = activateDefence("EMAIL_WHITELIST", defences);
+  defences = activateDefence(DEFENCE_TYPES.EMAIL_WHITELIST, defences);
   const whitelist = getEmailWhitelist(defences);
   expect(whitelist).toBe(
     "The whitelisted emails and domains are: " + process.env.EMAIL_WHITELIST
@@ -173,7 +174,7 @@ test("GIVEN email is not in whitelist WHEN checking whitelist THEN false is retu
   process.env.EMAIL_WHITELIST = "bob@example.com,kate@example.com";
   let defences = getInitialDefences();
   // activate email whitelist defence
-  defences = activateDefence("EMAIL_WHITELIST", defences);
+  defences = activateDefence(DEFENCE_TYPES.EMAIL_WHITELIST, defences);
   const address = "malicious@user.com";
   const isWhitelisted = isEmailInWhitelist(address, defences);
   expect(isWhitelisted).toBe(false);
@@ -183,7 +184,7 @@ test("GIVEN email is in whitelist WHEN checking whitelist THEN true is returned"
   process.env.EMAIL_WHITELIST = "bob@example.com,kate@example.com";
   let defences = getInitialDefences();
   // activate email whitelist defence
-  defences = activateDefence("EMAIL_WHITELIST", defences);
+  defences = activateDefence(DEFENCE_TYPES.EMAIL_WHITELIST, defences);
   const address = "bob@example.com";
   const isWhitelisted = isEmailInWhitelist(address, defences);
   expect(isWhitelisted).toBe(true);
@@ -193,7 +194,7 @@ test("GIVEN email domain is in whitelist WHEN checking whitelist THEN true is re
   process.env.EMAIL_WHITELIST = "@example.com";
   let defences = getInitialDefences();
   // activate email whitelist defence
-  defences = activateDefence("EMAIL_WHITELIST", defences);
+  defences = activateDefence(DEFENCE_TYPES.EMAIL_WHITELIST, defences);
   const address = "bob@example.com";
   const isWhitelisted = isEmailInWhitelist(address, defences);
   expect(isWhitelisted).toBe(true);
diff --git a/frontend/src/models/defence.ts b/frontend/src/models/defence.ts
index e9eda0e76..c72e224b4 100644
--- a/frontend/src/models/defence.ts
+++ b/frontend/src/models/defence.ts
@@ -2,10 +2,10 @@ enum DEFENCE_TYPES {
   CHARACTER_LIMIT = "CHARACTER_LIMIT",
   EMAIL_WHITELIST = "EMAIL_WHITELIST",
   LLM_EVALUATION = "LLM_EVALUATION",
+  QA_LLM_INSTRUCTIONS = "QA_LLM_INSTRUCTIONS",
   RANDOM_SEQUENCE_ENCLOSURE = "RANDOM_SEQUENCE_ENCLOSURE",
   SYSTEM_ROLE = "SYSTEM_ROLE",
   XML_TAGGING = "XML_TAGGING",
-  QA_LLM_INSTRUCTIONS = "QA_LLM_INSTRUCTIONS",
 }
 
 class DefenceConfig {
diff --git a/frontend/src/service/defenceService.ts b/frontend/src/service/defenceService.ts
index 90a42fa43..0cd83be0c 100644
--- a/frontend/src/service/defenceService.ts
+++ b/frontend/src/service/defenceService.ts
@@ -1,4 +1,4 @@
-import { DefenceConfig, DefenceInfo } from "../models/defence";
+import { DEFENCE_TYPES, DefenceConfig, DefenceInfo } from "../models/defence";
 import { sendRequest } from "./backendService";
 
 const PATH = "defence/";
@@ -60,9 +60,9 @@ function validateStringConfig(config: string) {
 
 function validateDefence(id: string, configName: string, config: string) {
   switch (id) {
-    case "CHARACTER_LIMIT":
+    case DEFENCE_TYPES.CHARACTER_LIMIT:
       return validateNumberConfig(config);
-    case "RANDOM_SEQUENCE_ENCLOSURE":
+    case DEFENCE_TYPES.RANDOM_SEQUENCE_ENCLOSURE:
       return configName === "length"
         ? validateNumberConfig(config)
         : validateStringConfig(config);