Being liable has nothing to do with whether or not someone carries insurance or not. Being liable has to do with not meeting one's duty of care. My employees can be minding there own business doing there work, a helicopter crashes through the roof and kills two of my employees - whether I have insurance or not and whether those employees are on the books or under the table, my company as the employer is not liable for their deaths. Now, can my employees family sue my company seeking damages? Sure they can. They'll probably lose and hopefully they have a good enough lawyer to sue the pilot/helicopter company. In reality they'll just sue anyone and everyone - basically they'll throw everything at the wall and see what sticks. In any event, we generally have a duty of care to others, certainly employers have a duty of care to their employees. Just because an employee dies on the job/at the workplace, does not automatically mean an employer has breached that duty of care and therefore has liability for said death.