It depends on how serious a punishment you are advocating in my opinion. Is probation and a fine enough?
No. They should all go back home and wait in line. If they don't arrest and deport.
No. Probation and a fine is not enough. Thirty days in jail and deportation is enough. On the first offense. Second offense let’s make it ninety. And if they try it again, two years. That would be enough. Now that I think about it, let’s skip the middle part and go straight to the two years.
Same for those who employ them.