Drupal: return a 403 response from a controller

response_403_in_controller.php

<?php

namespace Drupal\your_module\Controller;

use Symfony\Component\HttpKernel\Exception\AccessDeniedHttpException;

class YourController {
  public function yourPage() {
    // Some logic here...

    if (!$access) {
      throw new AccessDeniedHttpException();
    }