[2][3] From 1982 until 1985, Chen served as an associate at the San Francisco law firm of Coblentz, Cahen, McCabe & Breyer.

[2] In September 1985, Chen became a staff attorney for the American Civil Liberties Union, specializing in language discrimination cases.

[7] President Obama renominated Chen in January 2010, and the Senate Judiciary Committee approved his nomination on February 4, 2010.

[3] Chen's notable cases have included the civil trial regarding the shooting of Oscar Grant by a Bay Area Rapid Transit Police Department officer,[13] the criminal prosecution of former Korn Ferry executive David Nosal for hacking,[14] and a number of cases being brought against Uber regarding the classification of its drivers as independent contractors.

[15][16] On June 21, 2012, the charity fraud case of Carreon v. Inman et al, which has achieved some prominence on the Internet, was assigned to Chen.