diff --git a/http-requests/POST-blogposts.http b/http-requests/POST-blogposts.http
index 9c8703c..be58461 100644
--- a/http-requests/POST-blogposts.http
+++ b/http-requests/POST-blogposts.http
@@ -12,3 +12,19 @@ Content-Type: application/json
     client.assert(response.status === 201);
   });
 %}
+
+###
+
+POST {{endpoint}}/blogposts
+Accept: application/json
+Content-Type: application/json
+
+{
+  "content": "Das ist ein Test"
+}
+
+> {%
+  client.test("BlogPosts returned", () => {
+    client.assert(response.status === 400);
+  });
+%}
diff --git a/pom.xml b/pom.xml
index 02c2c38..ddba5a1 100644
--- a/pom.xml
+++ b/pom.xml
@@ -30,6 +30,10 @@
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-hateoas</artifactId>
     </dependency>
+    <dependency>
+      <groupId>org.springframework.boot</groupId>
+      <artifactId>spring-boot-starter-validation</artifactId>
+    </dependency>
 
     <dependency>
       <groupId>org.springframework.boot</groupId>
diff --git a/src/main/java/de/sample/schulung/spring/blog/boundary/GlobalExceptionHandler.java b/src/main/java/de/sample/schulung/spring/blog/boundary/GlobalExceptionHandler.java
new file mode 100644
index 0000000..5ed59f5
--- /dev/null
+++ b/src/main/java/de/sample/schulung/spring/blog/boundary/GlobalExceptionHandler.java
@@ -0,0 +1,19 @@
+package de.sample.schulung.spring.blog.boundary;
+
+import jakarta.validation.ConstraintViolationException;
+import org.springframework.http.HttpStatus;
+import org.springframework.web.bind.annotation.ExceptionHandler;
+import org.springframework.web.bind.annotation.ResponseStatus;
+import org.springframework.web.bind.annotation.RestControllerAdvice;
+
+@RestControllerAdvice
+public class GlobalExceptionHandler {
+
+  @ExceptionHandler(ConstraintViolationException.class)
+  @ResponseStatus(HttpStatus.BAD_REQUEST)
+  void handleValidationException() {
+    // do nothing
+    // return ResponseEntity, Fehler-Object (JSON), ProblemDetail
+  }
+
+}
diff --git a/src/main/java/de/sample/schulung/spring/blog/domain/BlogPost.java b/src/main/java/de/sample/schulung/spring/blog/domain/BlogPost.java
index 30b0c4b..0469cc8 100644
--- a/src/main/java/de/sample/schulung/spring/blog/domain/BlogPost.java
+++ b/src/main/java/de/sample/schulung/spring/blog/domain/BlogPost.java
@@ -1,5 +1,7 @@
 package de.sample.schulung.spring.blog.domain;
 
+import jakarta.validation.constraints.NotNull;
+import jakarta.validation.constraints.Size;
 import lombok.Builder;
 import lombok.Getter;
 import lombok.Setter;
@@ -13,7 +15,11 @@
 public class BlogPost {
 
   private UUID id;
+  @Size(min = 3)
+  @NotNull
   private String title;
+  @Size(min = 10)
+  @NotNull
   private String content;
   private LocalDateTime timestamp;
 
diff --git a/src/main/java/de/sample/schulung/spring/blog/domain/BlogPostService.java b/src/main/java/de/sample/schulung/spring/blog/domain/BlogPostService.java
index 29bc422..a595527 100644
--- a/src/main/java/de/sample/schulung/spring/blog/domain/BlogPostService.java
+++ b/src/main/java/de/sample/schulung/spring/blog/domain/BlogPostService.java
@@ -1,6 +1,9 @@
 package de.sample.schulung.spring.blog.domain;
 
+import jakarta.validation.Valid;
+import jakarta.validation.constraints.NotNull;
 import org.springframework.stereotype.Service;
+import org.springframework.validation.annotation.Validated;
 
 import java.time.LocalDateTime;
 import java.util.HashMap;
@@ -9,6 +12,7 @@
 import java.util.UUID;
 import java.util.stream.Stream;
 
+@Validated
 @Service
 public class BlogPostService {
 
@@ -24,7 +28,7 @@ public Optional<BlogPost> findById(UUID id) {
     );
   }
 
-  public void create(BlogPost blogPost) {
+  public void create(@Valid @NotNull BlogPost blogPost) {
     final var id = UUID.randomUUID();
     blogPost.setId(id);
     blogPost.setTimestamp(LocalDateTime.now());
diff --git a/src/test/java/de/sample/schulung/spring/blog/boundary/BlogPostApiTests.java b/src/test/java/de/sample/schulung/spring/blog/boundary/BlogPostApiTests.java
index a6f2a1b..d6a8fa1 100644
--- a/src/test/java/de/sample/schulung/spring/blog/boundary/BlogPostApiTests.java
+++ b/src/test/java/de/sample/schulung/spring/blog/boundary/BlogPostApiTests.java
@@ -62,6 +62,22 @@ void shouldCreateBlogPostSuccessfully() throws Exception {
 
   }
 
+  @Test
+  void shouldNotCreateInvalidBlogPost() throws Exception {
+    mvc.perform(
+        post("/blogposts")
+          .accept(MediaType.APPLICATION_JSON)
+          .contentType(MediaType.APPLICATION_JSON)
+          .content("""
+              {
+               "content": "Das ist ein Test"
+              }
+            """)
+      )
+      .andExpect(status().isBadRequest());
+
+  }
+
   /*
    * Testfall:
    *  - Lege BlogPost an (title: "test")
diff --git a/src/test/java/de/sample/schulung/spring/blog/boundary/BlogPostApiWithMockedServiceTests.java b/src/test/java/de/sample/schulung/spring/blog/boundary/BlogPostApiWithMockedServiceTests.java
index 836d14e..651cbbc 100644
--- a/src/test/java/de/sample/schulung/spring/blog/boundary/BlogPostApiWithMockedServiceTests.java
+++ b/src/test/java/de/sample/schulung/spring/blog/boundary/BlogPostApiWithMockedServiceTests.java
@@ -14,8 +14,10 @@
 import java.util.Optional;
 import java.util.UUID;
 
+import static org.mockito.Mockito.verifyNoInteractions;
 import static org.mockito.Mockito.when;
 import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post;
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
 
@@ -58,6 +60,23 @@ void shouldReturnSingleBlogPostSuccessfully() throws Exception {
       .andExpect(jsonPath("$.timestamp").exists());
   }
 
+  @Test
+  void shouldNotCreateInvalidBlogPost() throws Exception {
+    mvc.perform(
+        post("/blogposts")
+          .accept(MediaType.APPLICATION_JSON)
+          .contentType(MediaType.APPLICATION_JSON)
+          .content("""
+              {
+               "content": "Das ist ein Test"
+              }
+            """)
+      )
+      .andExpect(status().isBadRequest());
+    verifyNoInteractions(service);
+
+  }
+
 
   // TODO wenn ID im Request mitgeschickt wird -> ??