Thomas was born in San Diego. Thomas' father was a bookkeeper and her mother was a school custodian, neither of whom went to college.[3] She graduated from Stanford University in 2000 with a Bachelor of Arts degree with honors. Thomas worked as a client advocate for the San Francisco Bar Association's Volunteer Legal Services Program from 2000 to 2001. She then attended Yale Law School, where she was an essays editor for the Yale Law Journal, graduating with a Juris Doctor in 2004.[2][4]
On September 8, 2021, President Joe Biden announced his intent to nominate Thomas to serve as a United States circuit judge for the Ninth Circuit. On September 20, 2021, her nomination was sent to the Senate. President Biden nominated Thomas to the seat to be vacated by Judge William A. Fletcher, who announced his intent to assume senior status upon confirmation of a successor.[7] On October 20, 2021, a hearing on her nomination was held before the Senate Judiciary Committee.[8] During her confirmation hearing, Republican senators criticized her work as a civil rights attorney before becoming a Superior Court judge.[9] On December 2, 2021, the Senate Judiciary Committee failed to report her nomination by a 11–11 vote.[10] On December 16, 2021, the United States Senate discharged the committee from further consideration of her nomination by a 50–46 vote.[11] On December 17, 2021, Majority Leader Chuck Schumer filed cloture on her nomination.[12] On December 18, 2021, the Senate invoked cloture on her nomination by a 42–25 vote.[13] On January 20, 2022, her nomination was confirmed by a 48–40 vote.[14] She received her judicial commission on January 24, 2022.[6] Thomas became the first black woman to serve on the Ninth Circuit from California,[15] as well as the second black woman to ever serve on the Ninth Circuit after Johnnie B. Rawlinson.