[1] He received a Bachelor of Arts degree, magna cum laude, in 1986, from the American International College.

[1] On September 24, 2013, President Barack Obama nominated Mastroianni to serve on the court, to the seat vacated by Judge Michael Ponsor, who assumed senior status on August 15, 2011.

[4] Mastroianni was rated "well qualified" for the post by a substantial majority of the American Bar Association's Standing Committee on the Federal Judiciary.

In 2019, Mastroianni issued a decision siding with the challengers and holding that "fire cider" is a generic term.

[10][11][12] In 2017, Mastroianni dismissed a defamation lawsuit brought by Katherine Mae McKee against comedian Bill Cosby.