Try the following:
filters.php
Route::filter('role', function()
{
if ( Auth::user()->role !==1) {
// do something
return Redirect::to('/');
}
});
routes.php
Route::group(array('before' => 'role'), function() {
Route::get('customer/retrieve/{id}', 'CustomerController@retrieve_single');
Route::post('customer/create', 'CustomerController@create');
Route::put('customer/update/{id}', 'CustomerController@update');
});