Denver University law professor Cesar Cuauhtemoc Garcia Hernandez has been a harsh critic of U-S immigration policy, and has helped coin a word to describe that policy, "crimmigation." A term which refers to how immigration law, at one time, was a civil law proceeding, but today has merged with criminal law. Roughly 400,000 migrants are imprisoned each year, far more than Professor Garcia Hernandez says is necessary. Today's immigration detainee may be surprising. While most are applying for asylum, or held for illegal border crossings, many more are legal or protected residents who have run afoul of a minor law violation, many of which may have occurred years ago. Garcia Hernandez writes of some of the more egregious cases he's run across in his book, "Migrating to Prison: America's Obsession with Locking Up Immigrants." He is an associate professor of law at the University of Denver and writes the crimmigation.com legal blog.