[2][3] After graduating from law school, Collins served as a law clerk to Judge Dorothy Wright Nelson of the United States Court of Appeals for the Ninth Circuit from 1988 to 1989 and then to Justice Antonin Scalia of the Supreme Court of the United States from 1991 to 1992.

[4] He later served as an Associate United States Deputy Attorney General and in that role participated substantially in the drafting of the PROTECT Act of 2003.

[7] In 2009, he represented Phillip Morris in opposing a ban on tobacco sales in drug stores in San Francisco.

President Trump nominated Collins to the seat vacated by Judge Harry Pregerson, who assumed senior status on December 11, 2015.

[14] On January 3, 2019, his nomination was returned to the President under Rule XXXI, Paragraph 6 of the United States Senate.