Unfortunately, Laravel doesn't have anything built-in that will help you with this, but you can specify your own custom filter.

First, create a filter:

Route::filter('department', function ($route, $request) {
    // Check to see if the current user belongs to the department:
    $department_id = $request->segment(1);
    if (!Auth::user()->canAccessDepartment($department_id)) {
        // The user shouldn't be allowed to access the department! Redirect them
        return Redirect::to('/url/to/notice/here');
    }
});

You can use the Request::segment() method to get the Department ID from the URL. Replace canAccessDepartment with whatever logic you've actually defined.

Then apply the filter to the route(s):

Route::group(array('before' => 'department'), function () {
    Route::resource('department','DepartmentsController');
    Route::resource('department.project','ProjectsController');
});

(For help with this, check out the route filters section of the docs.)

Thank you, this sounds easy (now) :) .

One question left:

canAccessDepartment()

this method would need to be defined in User model or should be defined in filters.php ?

RokSiEu said: this method would need to be defined in User model or should be defined in filters.php ?

In my example, it would be defined in the User model. That's really your choice though. You basically just need to create some logic somewhere that determines whether a User is allowed to access a Department. You could even do it in the filter (but it's a good idea to keep that logic elsewhere):

if ($user->departments()->where('id', $department_id)->count() < 1) {
    // The user is not authorized
}