Index: src/main/java/com/db/finki/www/build_board/controller/thread_controller/TopicController.java
===================================================================
--- src/main/java/com/db/finki/www/build_board/controller/thread_controller/TopicController.java	(revision c5b7b7c6d1e67bb13d73bd9da868688bdaabdf84)
+++ src/main/java/com/db/finki/www/build_board/controller/thread_controller/TopicController.java	(revision e2fee85b1efd47fc5ad4f7e0b7b63de05e2ca149)
@@ -6,4 +6,5 @@
 import com.db.finki.www.build_board.entity.thread.Topic;
 import com.db.finki.www.build_board.entity.user_type.Moderator;
+import com.db.finki.www.build_board.service.BlacklistedUserService;
 import com.db.finki.www.build_board.service.ReportService;
 import com.db.finki.www.build_board.service.thread.impl.DiscussionService;
@@ -28,10 +29,12 @@
     private final String DUPLICATE_TITTLE = "There already exists a topic with title";
     private final ReportService reportService;
+    private final BlacklistedUserService  blacklistedUserService;
 
-    public TopicController(TopicService topicService, TagService tagService, DiscussionService discussionService, ReportService reportService) {
+    public TopicController(TopicService topicService, TagService tagService, DiscussionService discussionService, ReportService reportService, BlacklistedUserService blacklistedUserService) {
         this.topicService = topicService;
         this.tagService = tagService;
         this.discussionService = discussionService;
         this.reportService = reportService;
+        this.blacklistedUserService = blacklistedUserService;
     }
 
@@ -55,7 +58,13 @@
     @GetMapping("/{topic-id}")
     public String showTopic(@PathVariable(name = "topic-id") int topicId, Model model,
-            @RequestParam(required = false) Boolean duplicateTittle) {
+            @RequestParam(required = false) Boolean duplicateTittle,
+            @SessionAttribute() BBUser user) {
+
         if (duplicateTittle != null) {
             model.addAttribute("errMsg", "There already exists a thread with the same title in that parent");
+        }
+
+        if(blacklistedUserService.isBlacklisted(user.getId())) {
+            return "blacklisted";
         }
 
Index: src/main/java/com/db/finki/www/build_board/repository/BlacklistedUserRepo.java
===================================================================
--- src/main/java/com/db/finki/www/build_board/repository/BlacklistedUserRepo.java	(revision c5b7b7c6d1e67bb13d73bd9da868688bdaabdf84)
+++ src/main/java/com/db/finki/www/build_board/repository/BlacklistedUserRepo.java	(revision e2fee85b1efd47fc5ad4f7e0b7b63de05e2ca149)
@@ -4,5 +4,16 @@
 import com.db.finki.www.build_board.entity.blacklisted_user.BlacklistedUserId;
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.query.Param;
 
 public interface BlacklistedUserRepo extends JpaRepository<BlacklistedUser, BlacklistedUserId> {
+    @Query(nativeQuery = true,
+    value = """
+        select exists(
+                select *
+                from blacklisted_user bu
+                where bu.user_id=:userId
+        ) 
+    """)
+    boolean isUserInBlacklist(@Param("userId") long userId);
 }
Index: src/main/java/com/db/finki/www/build_board/service/BlacklistedUserService.java
===================================================================
--- src/main/java/com/db/finki/www/build_board/service/BlacklistedUserService.java	(revision e2fee85b1efd47fc5ad4f7e0b7b63de05e2ca149)
+++ src/main/java/com/db/finki/www/build_board/service/BlacklistedUserService.java	(revision e2fee85b1efd47fc5ad4f7e0b7b63de05e2ca149)
@@ -0,0 +1,15 @@
+package com.db.finki.www.build_board.service;
+
+import com.db.finki.www.build_board.repository.BlacklistedUserRepo;
+import org.springframework.stereotype.Service;
+
+@Service
+public class BlacklistedUserService {
+    private final BlacklistedUserRepo  blacklistedUserRepo;
+
+    public BlacklistedUserService(BlacklistedUserRepo blacklistedUserRepo) {this.blacklistedUserRepo = blacklistedUserRepo;}
+
+    public boolean isBlacklisted(long userId) {
+        return blacklistedUserRepo.isUserInBlacklist(userId);
+    }
+}
Index: src/main/resources/templates/blacklisted.html
===================================================================
--- src/main/resources/templates/blacklisted.html	(revision e2fee85b1efd47fc5ad4f7e0b7b63de05e2ca149)
+++ src/main/resources/templates/blacklisted.html	(revision e2fee85b1efd47fc5ad4f7e0b7b63de05e2ca149)
@@ -0,0 +1,31 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport"
+          content="width=device-width, initial-scale=1.0">
+    <title>
+        Add
+        Topic</title>
+    <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.0/dist/css/bootstrap.min.css"
+          rel="stylesheet">
+    <style>
+        .error-bubble {
+            display: inline-block;
+            background-color: #dc3545; /* Bootstrap danger color */
+            color: white;
+            padding: 10px 15px;
+            border-radius: 20px;
+            font-weight: bold;
+            box-shadow: 0px 4px 6px rgba(0, 0, 0, 0.2);
+        }
+    </style>
+</head>
+<body>
+<div th:replace="/home_pages/home :: navigation"></div>
+<main class="d-flex vh-100 justify-content-center align-items-center">
+    <h1 class="text-center">
+        The moderators have blacklisted you from this site
+    </h1>
+</main>
+</body>