Some notes in the code block below...

 /**
* Accepts the post request for login
* of user in CMS
*
*/
public function userLogin()
{
...

// returns validation object if fails, nothing if passes

// the single = looks off, but I normally don't make if's with var assignments in it

if ($errors = User::loginIsInvalid($user_credentials))
{
return Redirect::route('cms.login')->withInput()->withErrors($errors);
}

// if this passes then redirect to route('cms.home')

if (Auth::attempt(array(
'email' => $user_credentials['email'],
'password' => $user_credentials['password']), $remember_me))
{
return Redirect::route('cms.home');
}

// ??? what happens if auth fails it returns nothing, aka the white screen

} 

Hope that helps