Sannes received a Bachelor of Arts degree, magna cum laude, in 1980 from Carleton College.

She served as a law clerk to Judge Jerome Farris of the United States Court of Appeals for the Ninth Circuit, from 1983 to 1984.

From 1984 to 1988, she worked at the law firm of Wyman, Bautzer, Christensen, Kuchel & Silbert in Los Angeles.

[5] On November 18, 2014, Senate Majority Leader Harry Reid filed for cloture on her nomination.

On November 19, 2014, the United States Senate invoked cloture on her nomination by a 55–42 vote.