Change is in the air. States from Arizona to Virginia have enacted laws cracking down on illegal immigration. Some target the immigrants; some target their employers. Some rely on local police to do the job; others require that employers use the federal e-Verify system to check the immigration status of employees. Many of these statutes have been challenged in court. Some have been put on hold while others — including an Alabama statute regarded as the most stringent of all — have been endorsed by federal appeals judges. These initiatives share a common goal: enforcement of federal immigration laws, something...