• "Princeton University sociologist Douglas S. Massey reports that 62 percent of illegal immigrants pay income taxes (via withholding) and 66 percent contribute to Social Security."



• "Forbes magazine notes that Mexican illegals aren't clogging up the social-services system: only 5 percent receive food stamps or unemployment assistance; 10 percent send kids to public schools."



• Heather McDonald discovered that illegal immigrants in 2004 accounted for 95 percent of all outstanding homicide warrants in Los Angeles and two-thirds of unserved felony warrants. [...] On the other hand, the most comprehensive survey to date of national crime data concludes, "In the small number of studies providing empirical evidence, immigrants are generally less involved in crime than similarly situated groups, despite the wealth of prominent criminological theories that provide good reasons why this should not be the case."

Instead of immediately criminalizing the hiring of illegal immigrants, why don’t we try using the tax code first? Change the tax code to require employers prove that each employee is legally eligible to work in the US before the employer is permitted to deduct as business expenses the wages and benefits paid to that worker.

Employers could still hire illegal workers but their increased taxes would help internalize social costs of their actions.