diff --git a/app/Http/Controllers/Api/V1/InvitationController.php b/app/Http/Controllers/Api/V1/InvitationController.php
index 0786c72d..654628de 100644
--- a/app/Http/Controllers/Api/V1/InvitationController.php
+++ b/app/Http/Controllers/Api/V1/InvitationController.php
@@ -60,7 +60,7 @@ class InvitationController extends Controller
             $this->user(),
             $organization,
             $request->input('email'),
-            $request->input('role')
+            $request->getRole()->value
         );
 
         return response()->json(null, 204);
diff --git a/app/Http/Controllers/Api/V1/MemberController.php b/app/Http/Controllers/Api/V1/MemberController.php
index b0eaf22a..c5eab462 100644
--- a/app/Http/Controllers/Api/V1/MemberController.php
+++ b/app/Http/Controllers/Api/V1/MemberController.php
@@ -68,7 +68,7 @@ class MemberController extends Controller
             $member->billable_rate = $request->getBillableRate();
         }
         if ($request->has('role')) {
-            $member->role = $request->input('role');
+            $member->role = $request->getRole()->value;
         }
         $member->save();
 
diff --git a/app/Http/Requests/V1/Invitation/InvitationStoreRequest.php b/app/Http/Requests/V1/Invitation/InvitationStoreRequest.php
index dc02996a..9f479bc8 100644
--- a/app/Http/Requests/V1/Invitation/InvitationStoreRequest.php
+++ b/app/Http/Requests/V1/Invitation/InvitationStoreRequest.php
@@ -30,9 +30,14 @@ class InvitationStoreRequest extends FormRequest
             'role' => [
                 'required',
                 'string',
-                // TODO: placeholder role should not be allowed
-                Rule::enum(Role::class),
+                Rule::enum(Role::class)
+                    ->except([Role::Owner, Role::Placeholder]),
             ],
         ];
     }
+
+    public function getRole(): Role
+    {
+        return Role::from($this->input('role'));
+    }
 }
diff --git a/app/Http/Requests/V1/Member/MemberUpdateRequest.php b/app/Http/Requests/V1/Member/MemberUpdateRequest.php
index eaaa1bb4..e7defb67 100644
--- a/app/Http/Requests/V1/Member/MemberUpdateRequest.php
+++ b/app/Http/Requests/V1/Member/MemberUpdateRequest.php
@@ -25,8 +25,8 @@ class MemberUpdateRequest extends FormRequest
         return [
             'role' => [
                 'string',
-                // TODO: placeholder role should not be allowed
-                Rule::enum(Role::class),
+                Rule::enum(Role::class)
+                    ->except([Role::Owner, Role::Placeholder]),
             ],
             'billable_rate' => [
                 'nullable',
@@ -52,4 +52,9 @@ class MemberUpdateRequest extends FormRequest
         return $this->has('billable_rate_update_time_entries') &&
             $this->input('billable_rate_update_time_entries') === 'true';
     }
+
+    public function getRole(): Role
+    {
+        return Role::from($this->input('role'));
+    }
 }
diff --git a/tests/Unit/Endpoint/Api/V1/InvitationEndpointTest.php b/tests/Unit/Endpoint/Api/V1/InvitationEndpointTest.php
index c0bc6c23..00209a94 100644
--- a/tests/Unit/Endpoint/Api/V1/InvitationEndpointTest.php
+++ b/tests/Unit/Endpoint/Api/V1/InvitationEndpointTest.php
@@ -57,8 +57,7 @@ class InvitationEndpointTest extends ApiEndpointTestAbstract
     public function test_store_fails_if_user_has_no_permission_to_create_invitations(): void
     {
         // Arrange
-        $data = $this->createUserWithPermission([
-        ]);
+        $data = $this->createUserWithPermission();
         Passport::actingAs($data->user);
 
         // Act
@@ -71,6 +70,44 @@ class InvitationEndpointTest extends ApiEndpointTestAbstract
         $response->assertStatus(403);
     }
 
+    public function test_store_fails_if_user_invites_with_role_owner(): void
+    {
+        // Arrange
+        $data = $this->createUserWithPermission([
+            'invitations:create',
+        ]);
+        Passport::actingAs($data->user);
+
+        // Act
+        $response = $this->postJson(route('api.v1.invitations.store', $data->organization->getKey()), [
+            'email' => 'test@asdf.at',
+            'role' => Role::Owner->value,
+        ]);
+
+        // Assert
+        $response->assertStatus(422);
+        $response->assertJsonPath('message', 'The selected role is invalid.');
+    }
+
+    public function test_store_fails_if_user_invites_with_role_placeholder(): void
+    {
+        // Arrange
+        $data = $this->createUserWithPermission([
+            'invitations:create',
+        ]);
+        Passport::actingAs($data->user);
+
+        // Act
+        $response = $this->postJson(route('api.v1.invitations.store', $data->organization->getKey()), [
+            'email' => 'test@asdf.at',
+            'role' => Role::Placeholder->value,
+        ]);
+
+        // Assert
+        $response->assertStatus(422);
+        $response->assertJsonPath('message', 'The selected role is invalid.');
+    }
+
     public function test_store_invites_user_to_organization(): void
     {
         // Arrange
diff --git a/tests/Unit/Endpoint/Api/V1/MemberEndpointTest.php b/tests/Unit/Endpoint/Api/V1/MemberEndpointTest.php
index 3be1142e..79c1e56d 100644
--- a/tests/Unit/Endpoint/Api/V1/MemberEndpointTest.php
+++ b/tests/Unit/Endpoint/Api/V1/MemberEndpointTest.php
@@ -136,6 +136,63 @@ class MemberEndpointTest extends ApiEndpointTestAbstract
         $this->assertSame(10001, $member->billable_rate);
     }
 
+    public function test_update_member_can_update_role(): void
+    {
+        // Arrange
+        $data = $this->createUserWithPermission([
+            'members:update',
+        ]);
+        $otherUser = User::factory()->create();
+        $otherMember = Member::factory()->forUser($otherUser)->forOrganization($data->organization)->role(Role::Employee)->create();
+        Passport::actingAs($data->user);
+
+        // Act
+        $response = $this->putJson(route('api.v1.members.update', [$data->organization->getKey(), $otherMember->getKey()]), [
+            'role' => Role::Admin->value,
+        ]);
+
+        // Assert
+        $response->assertStatus(200);
+        $otherMember->refresh();
+        $this->assertSame(Role::Admin->value, $otherMember->role);
+    }
+
+    public function test_update_member_role_fails_if_role_is_owner(): void
+    {
+        // Arrange
+        $data = $this->createUserWithPermission([
+            'members:update',
+        ]);
+        Passport::actingAs($data->user);
+
+        // Act
+        $response = $this->putJson(route('api.v1.members.update', [$data->organization->getKey(), $data->member->getKey()]), [
+            'role' => Role::Owner->value,
+        ]);
+
+        // Assert
+        $response->assertStatus(422);
+        $response->assertJsonPath('message', 'The selected role is invalid.');
+    }
+
+    public function test_update_member_role_fails_if_role_is_placeholder(): void
+    {
+        // Arrange
+        $data = $this->createUserWithPermission([
+            'members:update',
+        ]);
+        Passport::actingAs($data->user);
+
+        // Act
+        $response = $this->putJson(route('api.v1.members.update', [$data->organization->getKey(), $data->member->getKey()]), [
+            'role' => Role::Placeholder->value,
+        ]);
+
+        // Assert
+        $response->assertStatus(422);
+        $response->assertJsonPath('message', 'The selected role is invalid.');
+    }
+
     public function test_invite_placeholder_succeeds_if_data_is_valid(): void
     {
         $data = $this->createUserWithPermission([