Until the 1980s, there were relatively few federal criminal prosecutions for violations of the immigration laws. Much has changed since then. Today, immigration offenses are the single largest offense type among all federal criminal prosecutions, accounting for between 30 and 40 percent of all federal felonies and Class A misdemeanors in recent years. Every year, there are also tens of thousands of prosecutions for Class B misdemeanor immigration offenses. In the federal districts along the...