diff --git a/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/checks/GameLobbyExistsCheck.java b/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/checks/GameLobbyExistsCheck.java
new file mode 100644
index 0000000..fba5240
--- /dev/null
+++ b/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/checks/GameLobbyExistsCheck.java
@@ -0,0 +1,75 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.app.checks;
+
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.bet.PlayerBetRequest;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.call.PlayerCallRequest;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.fold.PlayerFoldRequest;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.raise.PlayerRaiseRequest;
+import ch.unibas.dmi.dbis.cs108.casono.server.domain.lobby.Lobby;
+import ch.unibas.dmi.dbis.cs108.casono.server.domain.lobby.LobbyId;
+import ch.unibas.dmi.dbis.cs108.casono.server.domain.lobby.LobbyManager;
+import ch.unibas.dmi.dbis.cs108.casono.server.domain.user.User;
+import ch.unibas.dmi.dbis.cs108.casono.server.domain.user.UserRegistry;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.command.execution.checks.HandlerCheck;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.request.Request;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.response.ErrorResponse;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.response.Response;
+import java.util.Optional;
+
+/**
+ * Checks whether a target lobby exists for game action commands.
+ *
+ * <p>Supported commands are BET, CALL, FOLD and RAISE. If a request specifies a GAME_ID, the check
+ * validates that this lobby exists. Otherwise, it validates that the logged-in user is in a lobby.
+ */
+public class GameLobbyExistsCheck implements HandlerCheck {
+    private final UserRegistry userRegistry;
+    private final LobbyManager lobbyManager;
+
+    public GameLobbyExistsCheck(UserRegistry userRegistry, LobbyManager lobbyManager) {
+        this.userRegistry = userRegistry;
+        this.lobbyManager = lobbyManager;
+    }
+
+    @Override
+    public Optional<Response> check(Request request) {
+        Integer gameId = extractGameId(request);
+        User user = userRegistry.getBySessionId(request.getSessionId()).get();
+
+        Lobby lobby;
+        if (gameId != null) {
+            lobby = lobbyManager.getLobby(LobbyId.of(gameId));
+        } else {
+            lobby = lobbyManager.getLobbyByUsername(user.getName());
+        }
+
+        if (lobby != null) {
+            return Optional.empty();
+        }
+
+        if (gameId != null) {
+            return Optional.of(
+                    new ErrorResponse(request.getContext(), "LOBBY_NOT_FOUND", "Lobby not found"));
+        }
+
+        return Optional.of(
+                new ErrorResponse(request.getContext(), "NOT_IN_LOBBY", "User not in a lobby"));
+    }
+
+    private Integer extractGameId(Request request) {
+        if (request instanceof PlayerBetRequest) {
+            return ((PlayerBetRequest) request).getGameId();
+        }
+        if (request instanceof PlayerCallRequest) {
+            return ((PlayerCallRequest) request).getGameId();
+        }
+        if (request instanceof PlayerFoldRequest) {
+            return ((PlayerFoldRequest) request).getGameId();
+        }
+        if (request instanceof PlayerRaiseRequest) {
+            return ((PlayerRaiseRequest) request).getGameId();
+        }
+
+        throw new IllegalStateException(
+                "GameLobbyExistsCheck is only supported for BET, CALL, FOLD and RAISE requests");
+    }
+}
diff --git a/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/game/bet/PlayerBetHandler.java b/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/game/bet/PlayerBetHandler.java
index a37ebce..11c6ee3 100644
--- a/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/game/bet/PlayerBetHandler.java
+++ b/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/game/bet/PlayerBetHandler.java
@@ -1,7 +1,10 @@
 package ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.bet;
 
+import ch.unibas.dmi.dbis.cs108.casono.server.app.checks.GameLobbyExistsCheck;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.checks.UserLoggedInCheck;
 import ch.unibas.dmi.dbis.cs108.casono.server.domain.game.GameController;
 import ch.unibas.dmi.dbis.cs108.casono.server.domain.game.player.PlayerId;
+import ch.unibas.dmi.dbis.cs108.casono.server.domain.lobby.Lobby;
 import ch.unibas.dmi.dbis.cs108.casono.server.domain.lobby.LobbyId;
 import ch.unibas.dmi.dbis.cs108.casono.server.domain.lobby.LobbyManager;
 import ch.unibas.dmi.dbis.cs108.casono.server.domain.user.User;
@@ -41,6 +44,8 @@ public class PlayerBetHandler extends CommandHandler<PlayerBetRequest> {
         super(responseDispatcher);
         this.userRegistry = userRegistry;
         this.lobbyManager = lobbyManager;
+        addCheck(new UserLoggedInCheck(userRegistry));
+        addCheck(new GameLobbyExistsCheck(userRegistry, lobbyManager));
     }
 
     /**
@@ -69,22 +74,11 @@ public class PlayerBetHandler extends CommandHandler<PlayerBetRequest> {
         String username = opt.get().getName();
 
         Integer gameId = request.getGameId();
-        var lobby =
-                (gameId != null)
-                        ? lobbyManager.getLobby(LobbyId.of(gameId))
-                        : lobbyManager.getLobbyByUsername(username);
-
-        if (lobby == null) {
-            if (gameId != null) {
-                responseDispatcher.dispatch(
-                        new ErrorResponse(
-                                request.getContext(), "LOBBY_NOT_FOUND", "Lobby not found"));
-            } else {
-                responseDispatcher.dispatch(
-                        new ErrorResponse(
-                                request.getContext(), "NOT_IN_LOBBY", "User not in a lobby"));
-            }
-            return;
+        Lobby lobby;
+        if (gameId != null) {
+            lobby = lobbyManager.getLobby(LobbyId.of(gameId));
+        } else {
+            lobby = lobbyManager.getLobbyByUsername(username);
         }
 
         GameController game = lobby.getGameController();
diff --git a/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/game/call/PlayerCallHandler.java b/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/game/call/PlayerCallHandler.java
index b1c3618..3dcc013 100644
--- a/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/game/call/PlayerCallHandler.java
+++ b/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/game/call/PlayerCallHandler.java
@@ -1,7 +1,10 @@
 package ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.call;
 
+import ch.unibas.dmi.dbis.cs108.casono.server.app.checks.GameLobbyExistsCheck;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.checks.UserLoggedInCheck;
 import ch.unibas.dmi.dbis.cs108.casono.server.domain.game.GameController;
 import ch.unibas.dmi.dbis.cs108.casono.server.domain.game.player.PlayerId;
+import ch.unibas.dmi.dbis.cs108.casono.server.domain.lobby.Lobby;
 import ch.unibas.dmi.dbis.cs108.casono.server.domain.lobby.LobbyId;
 import ch.unibas.dmi.dbis.cs108.casono.server.domain.lobby.LobbyManager;
 import ch.unibas.dmi.dbis.cs108.casono.server.domain.user.User;
@@ -37,6 +40,8 @@ public class PlayerCallHandler extends CommandHandler<PlayerCallRequest> {
         super(responseDispatcher);
         this.userRegistry = userRegistry;
         this.lobbyManager = lobbyManager;
+        addCheck(new UserLoggedInCheck(userRegistry));
+        addCheck(new GameLobbyExistsCheck(userRegistry, lobbyManager));
     }
 
     /**
@@ -57,22 +62,11 @@ public class PlayerCallHandler extends CommandHandler<PlayerCallRequest> {
         String username = opt.get().getName();
 
         Integer gameId = request.getGameId();
-        var lobby =
-                (gameId != null)
-                        ? lobbyManager.getLobby(LobbyId.of(gameId))
-                        : lobbyManager.getLobbyByUsername(username);
-
-        if (lobby == null) {
-            if (gameId != null) {
-                responseDispatcher.dispatch(
-                        new ErrorResponse(
-                                request.getContext(), "LOBBY_NOT_FOUND", "Lobby not found"));
-            } else {
-                responseDispatcher.dispatch(
-                        new ErrorResponse(
-                                request.getContext(), "NOT_IN_LOBBY", "User not in a lobby"));
-            }
-            return;
+        Lobby lobby;
+        if (gameId != null) {
+            lobby = lobbyManager.getLobby(LobbyId.of(gameId));
+        } else {
+            lobby = lobbyManager.getLobbyByUsername(username);
         }
 
         GameController game = lobby.getGameController();
diff --git a/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/game/fold/PlayerFoldHandler.java b/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/game/fold/PlayerFoldHandler.java
index 7adca85..0aafca7 100644
--- a/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/game/fold/PlayerFoldHandler.java
+++ b/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/game/fold/PlayerFoldHandler.java
@@ -1,7 +1,10 @@
 package ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.fold;
 
+import ch.unibas.dmi.dbis.cs108.casono.server.app.checks.GameLobbyExistsCheck;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.checks.UserLoggedInCheck;
 import ch.unibas.dmi.dbis.cs108.casono.server.domain.game.GameController;
 import ch.unibas.dmi.dbis.cs108.casono.server.domain.game.player.PlayerId;
+import ch.unibas.dmi.dbis.cs108.casono.server.domain.lobby.Lobby;
 import ch.unibas.dmi.dbis.cs108.casono.server.domain.lobby.LobbyId;
 import ch.unibas.dmi.dbis.cs108.casono.server.domain.lobby.LobbyManager;
 import ch.unibas.dmi.dbis.cs108.casono.server.domain.user.User;
@@ -37,6 +40,8 @@ public class PlayerFoldHandler extends CommandHandler<PlayerFoldRequest> {
         super(responseDispatcher);
         this.userRegistry = userRegistry;
         this.lobbyManager = lobbyManager;
+        addCheck(new UserLoggedInCheck(userRegistry));
+        addCheck(new GameLobbyExistsCheck(userRegistry, lobbyManager));
     }
 
     /**
@@ -57,22 +62,11 @@ public class PlayerFoldHandler extends CommandHandler<PlayerFoldRequest> {
         String username = opt.get().getName();
 
         Integer gameId = request.getGameId();
-        var lobby =
-                (gameId != null)
-                        ? lobbyManager.getLobby(LobbyId.of(gameId))
-                        : lobbyManager.getLobbyByUsername(username);
-
-        if (lobby == null) {
-            if (gameId != null) {
-                responseDispatcher.dispatch(
-                        new ErrorResponse(
-                                request.getContext(), "LOBBY_NOT_FOUND", "Lobby not found"));
-            } else {
-                responseDispatcher.dispatch(
-                        new ErrorResponse(
-                                request.getContext(), "NOT_IN_LOBBY", "User not in a lobby"));
-            }
-            return;
+        Lobby lobby;
+        if (gameId != null) {
+            lobby = lobbyManager.getLobby(LobbyId.of(gameId));
+        } else {
+            lobby = lobbyManager.getLobbyByUsername(username);
         }
 
         GameController game = lobby.getGameController();
diff --git a/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/game/raise/PlayerRaiseHandler.java b/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/game/raise/PlayerRaiseHandler.java
index c17b11c..a089603 100644
--- a/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/game/raise/PlayerRaiseHandler.java
+++ b/src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/app/commands/game/raise/PlayerRaiseHandler.java
@@ -1,7 +1,10 @@
 package ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.raise;
 
+import ch.unibas.dmi.dbis.cs108.casono.server.app.checks.GameLobbyExistsCheck;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.checks.UserLoggedInCheck;
 import ch.unibas.dmi.dbis.cs108.casono.server.domain.game.GameController;
 import ch.unibas.dmi.dbis.cs108.casono.server.domain.game.player.PlayerId;
+import ch.unibas.dmi.dbis.cs108.casono.server.domain.lobby.Lobby;
 import ch.unibas.dmi.dbis.cs108.casono.server.domain.lobby.LobbyId;
 import ch.unibas.dmi.dbis.cs108.casono.server.domain.lobby.LobbyManager;
 import ch.unibas.dmi.dbis.cs108.casono.server.domain.user.User;
@@ -41,6 +44,8 @@ public class PlayerRaiseHandler extends CommandHandler<PlayerRaiseRequest> {
         super(responseDispatcher);
         this.userRegistry = userRegistry;
         this.lobbyManager = lobbyManager;
+        addCheck(new UserLoggedInCheck(userRegistry));
+        addCheck(new GameLobbyExistsCheck(userRegistry, lobbyManager));
     }
 
     /**
@@ -71,22 +76,11 @@ public class PlayerRaiseHandler extends CommandHandler<PlayerRaiseRequest> {
         String username = opt.get().getName();
 
         Integer gameId = request.getGameId();
-        var lobby =
-                (gameId != null)
-                        ? lobbyManager.getLobby(LobbyId.of(gameId))
-                        : lobbyManager.getLobbyByUsername(username);
-
-        if (lobby == null) {
-            if (gameId != null) {
-                responseDispatcher.dispatch(
-                        new ErrorResponse(
-                                request.getContext(), "LOBBY_NOT_FOUND", "Lobby not found"));
-            } else {
-                responseDispatcher.dispatch(
-                        new ErrorResponse(
-                                request.getContext(), "NOT_IN_LOBBY", "User not in a lobby"));
-            }
-            return;
+        Lobby lobby;
+        if (gameId != null) {
+            lobby = lobbyManager.getLobby(LobbyId.of(gameId));
+        } else {
+            lobby = lobbyManager.getLobbyByUsername(username);
         }
 
         GameController game = lobby.getGameController();