Born in Rio Piedras, Puerto Rico, Guzman received a Bachelor of Arts degree from Lehigh University in 1970 and a Juris Doctor from New York University Law School in 1973.
He was in private practice from 1973 to 1974, and was an assistant states attorney of Cook County, Illinois from 1975 to 1980.
He was a staff attorney (part-time), for the Association House of Chicago from 1980 to 1984, returning to private practice in Chicago, Illinois from 1980 to 1990.
He served as a United States magistrate judge for the United States District Court for the Northern District of Illinois from 1990 to 1999.
On August 5, 1999, Guzman was nominated by President Bill Clinton to a seat on the United States District Court for the Northern District of Illinois vacated by Brian Barnett Duff.