Hard cases make bad law

A good article here.

The yawning divide between reality and what such laws say should happen is what produces the dilemmas that lead to amnesties. Immigration law has produced a situation where an estimated 12 million people in the country -- most of whom look, sound and act like law-abiding citizens -- are supposed to be apprehended, prosecuted and deported, a job that is not only well beyond the capacity of the police and courts, but would wreck substantial parts of the economy were it attempted.

"No one is so stupid as to think police are going to go out and round up 12 million illegal immigrants," said Husak, at Rutgers University. "Ninety million living Americans have used illegal drugs. It is inconceivable you can punish them. Downloading copyrighted music [without paying for it] -- half or more of all teenagers are guilty. No one is going to enforce such laws."