[4] In 1984, Mosman clerked for Malcolm Richard Wilkey, judge on the United States Court of Appeals for the District of Columbia Circuit.

[3] While clerking for Powell, he was involved in the justice's voting to uphold Georgia's sodomy law in Bowers v. Hardwick,[6] writing[7] and After leaving Powell's employ, Mosman entered private practice in Portland, Oregon, in 1986 at Miller Nash (now Miller Nash Graham & Dunn).

[3] Senators Ron Wyden and Gordon H. Smith spoke at the confirmation hearing, highlighting his prior service in the war on terrorism and that a bipartisan commission established to fill the vacancy left by Robert E. Jones had discovered him.

[3] On February 1, 2008, in Lemons v. Bradbury, Mosman dismissed the lawsuit and lifted an injunction against Oregon's new civil union law.

[10] Mosman had issued the temporary injunction in December 2007 to prevent Oregon's new civil union law from taking effect in January.

[6] This was in response to a legal challenge by a group that had attempted to place a referendum on the November 2008 ballot to block the civil union law that had been passed by the Oregon Legislative Assembly.

[6] In 2017, Mosman approved renewal of a FISA Court warrant for Carter Page, a former adviser to the 2016 Trump Campaign.

[14] In April, 2020, Mosman granted Nike's motion dismissing Kawhi Leonard's copyright claims over a disputed logo, writing In July 2020, the Oregon Attorney General, Ellen Rosenblum, requested a restraining order based on the detainment actions of Department of Homeland Security and Customs and Border Patrol personnel.