Mark Kleiman makes yet another good point about immigration here. Immigration reform bills that increase penalties for illegal immigrants themselveslike Jim Sensenbrenner's bill which would make residing in this country illegally a felonywill only make it harder to penalize the actual businesses who hire illegal immigrants, because the undocumented workers will be deterred from doing any whistle-blowing. And it's hard to catch companies breaking the law without whistleblowers.
Meanwhile, steep penalties that deter illegal immigrants from testifying or complaining about their work conditions only makes them more attractive to employers, more likely to be hired, and more likely to be exploitedwhich contributes heavily towards depressing wages for native workers. Finally, as Kleiman points out, steep penalties for makes them more likely to become the victims of crimesince they're less likely to report anything to the police, for fear of deportation.
If Congress really wanted to slow down illegal immigration, they'd give the immigrants themselves every incentive to blow the whistle on companies hiring illegal immigrantsperhaps by granting citizenship to any immigrant who can she that he or she was illegally hired by a companyand then levy very steep penalties on law-breaking firms. The problem is that the businesses themselves tend to have well-paid lobbyists who can stop these sorts of provisions and penalties, while undocumented voters don't have, for obvious reasons, much of a voice in Congress.