| Mary Kay Costello | |
| Office: | Judge of the United States District Court for the Eastern District of Pennsylvania |
| Term Start: | September 19, 2024 |
| Appointer: | Joe Biden |
| Predecessor: | Cynthia M. Rufe |
| Office1: | Magistrate Judge of the United States District Court for the Eastern District of Pennsylvania |
| Term Start1: | August 2024 |
| Term End1: | September 19, 2024 |
| Birth Name: | Mary Kathleen Costello |
| Birth Place: | Bristol, Pennsylvania, U.S. |
| Education: | Temple University (BA, JD) |
| Allegiance: |  United States |
| Serviceyears: | 1986–1994 |
| Rank: | Staff sergeant |
Mary Kathleen Costello (born 1968)[1] is an American lawyer who has served as a United States district judge of the United States District Court for the Eastern District of Pennsylvania since September 2024. She previously served as a magistrate judge of the same court from August 2024 to September 2024.
Costello earned a Bachelor of Arts, summa cum laude, from Temple University in 1998 and a Juris Doctor, magna cum laude, from Temple University Beasley School of Law in 2001.[2]
Costello joined the U.S. Air Force in 1986. She served for eight years as a cyber-systems operator, receiving an honorable discharge in 1994 as a staff sergeant.[3]
From 2001 to 2004, Costello was an associate at Saul Ewing LLP and from 2004 to 2008, she was a litigation associate at Akin Gump Strauss Hauer & Feld. From 2008 to 2024, she served as an assistant United States attorney in the U.S. Attorney's Office for the Eastern District of Pennsylvania, where she prosecuted cases that include public corruption, fraud, and drug trafficking.[3] In August 2024, she left the office while her nomination was pending to be sworn in to serve as a magistrate judge of the United States District Court for the Eastern District of Pennsylvania.[4]
On June 12, 2024, President Joe Biden announced his intent to nominate Costello to serve as a United States district judge of the United States District Court for the Eastern District of Pennsylvania. On June 13, 2024, her nomination was sent to the Senate. President Biden nominated Costello to the seat vacated by Judge Cynthia M. Rufe, who assumed senior status on December 31, 2021.[5] On July 10, 2024, a hearing on her nomination was held before the Senate Judiciary Committee.[6] On August 1, 2024, her nomination was reported out of committee by a 13–7 vote.[7] On September 17, 2024, the United States Senate invoked cloture on her nomination by a 54–42 vote.[8] Later that day, her nomination was confirmed by a 52–41 vote.[9] [4] With her confirmation, Costello is President Biden's 12th LGBT appointed judge.[10] She received her judicial commission on September 19, 2024.