I would be in favor of such a law.
Not the tarring and feathering, etc., but fining the employers so it hurts? Absolutely!
And such a law should be rigorously enforced.
Then, when all the cheap labor dries up and the business owners howl like wounded animals, something appropriate will be done about this problem.
The US wants Mexican workers or they wouldn't be here. They ought to be able to come legally, but there's too much profit to be made from the present system.