Maybe I am wrong but I don't see an HTML form here and it looks like you are trying to submit the checkboxes using a link.

<form action="{{ route('user.tasks.destroy',array( $Task->id )) }}" method="post" >
<div class="dropdown">
        @foreach($LIST_OF_ITEMS_TO_DELETE as $ITEM_TO_DELETE)
        <input id="check1" name="deleteCheckedTask[]" type="checkbox" class="check" value="{{$ITEM_TO_DELETE->id}}">
        <span class="caret-hover caret"></span>
        @endforeach
    <ul class="dropdown-menu" aria-labelledby="selDelete" role="menu">
        <li><input type="submit" value="Delete Selected" /></li>
    </ul>   
</div>
</form>

Hi thanks for your answer and I see what you mean. I wanted to test your code but it changed the layout of the buttons: link: http://i.imgur.com/ESqYpVe.png

I think it's because of the submit button (which I also don't see in the browser for some reason). I'm really tired at the moment, so I'm going to sleep now.

Why do you have the checkbox in a button?

I would have one checkbox per row, then a single "delete selected" button which submits the form