In a New York Times op-ed, "Deportation Nation," law professor Daniel Kanstroom explains the horrors of America deporting aliens who are convicted of subsequent crimes.
To be sure, some deportees have been convicted of serious crimes. But most are guilty of drug offenses, or misdemeanors like petty larceny, simple assault, drunken driving.
Kanstroom explains that we must stop deporting them because they often become victims of discrimination in their home countries:
In a study of Latin American deportees who had lived for long periods in the United States (on average, 14 years), the sociologists M. Kathleen Dingeman and Rubén G. Rumbaut found that deportees who had emigrated as children suffered the most. Deportees to El Salvador (a country many had fled during the civil war of the 1980s) encountered discrimination because of their accents, style of dress and California gang-themed tattoos. [Bolding mine]