Peter Douglas Keisler (born October 13, 1960) is an American lawyer whose 2006 nomination by President George W. Bush to the United States Court of Appeals for the District of Columbia Circuit became embroiled in partisan controversy.

He is a partner at the firm of Sidley Austin in Washington, D.C., and used to be the Assistant Attorney General in charge of the Civil Division at the U.S. Department of Justice.

After finishing his Supreme Court clerkship, Keisler became a partner in the Washington, D.C. office of Sidley Austin.

He has also represented the government in defense of laws protecting access to abortion clinics and imposing requirements on telemarketing companies.

[3] In addition, he personally led the team that responded to a legal appeal by Sabin Willett, the lawyer for the seventeen remaining Uyghur captives in Guantanamo,[4] that tested the use of a provision of the Detainee Treatment Act in terms of whether or not captives could challenge the rulings of their Combatant Status Review Tribunals.

On September 6, 2007, Keisler announced his resignation from the Department of Justice in order to "spend time with his family.

After the 2006 midterm congressional elections (in which the Democrats reclaimed control of the Senate), President Bush renominated Keisler on November 15, 2006.

First, he was a co-founder of the Federalist Society, a conservative legal group which many Democrats saw as seeking to control the federal judiciary.

Third, during Keisler's tenure at the United States Department of Justice, he was instrumental in defending some of the most controversial policies of Republican President George W. Bush concerning the Global War on Terror.

[11] On March 18, 2008, it was announced that Keisler would be returning to his former position as a partner of Sidley Austin as a global coordinator of the firm's appellate practice in its Washington, D.C.