freescout/app/Policies/ThreadPolicy.php

<?php

namespace App\Policies;

use App\Thread;
use App\User;
use Illuminate\Auth\Access\HandlesAuthorization;

class ThreadPolicy
{
    use HandlesAuthorization;

    /**
     * Determine whether the user can edit the thread.
     *
     * @param \App\User    $user
     * @param \App\Thread  $thread
     *
     * @return mixed
     */
    public function edit(User $user, Thread $thread)
    {
        if ($thread->created_by_user_id 
            && in_array($thread->type, [Thread::TYPE_MESSAGE, Thread::TYPE_NOTE])
            && ($user->isAdmin() || ($user->hasPermission(User::PERM_EDIT_CONVERSATIONS) && $thread->created_by_user_id == $user->id))
        ) {
            return true;
        } else {
            return false;
        }
    }
}