[5] Robertson spent his last two years in the navy on desk duty at the Office of Naval Intelligence at The Pentagon and simultaneously attended the George Washington University Law School as a night student.

[6] After leaving the navy, he finished his third year as a day student, and was editor-in-chief of The George Washington Law Review.

[3][1][2] With the exception of a three-year gap from 1969 to 1972, Robertson was in private practice in Washington, D.C., from 1965 to 1994 at the law firm of Wilmer, Cutler & Pickering.

[1][2] While at Wilmer, Cutler & Pickering, Robertson worked under Louis F. Oberdorfer and later represented the Automobile Manufacturers Association in connection with the development of Federal Motor Vehicle Safety Standards.

[7] From 1969 to 1972, when Robertson served with the Lawyers' Committee for Civil Rights Under Law, as chief counsel at the organization's offices in Jackson, Mississippi (1969–1970) and as national director in Washington, D.C.

[10] In 2013, following his retirement from the judiciary, Robertson testified before the Privacy and Civil Liberties Oversight Board (PCLOB) and said that he had resigned in protest of the George W. Bush administration's warrantless wiretaps, which bypassed the FISA Court.

[11] Robertson also criticized the 2008 amendments to the Foreign Intelligence Surveillance Act, in which Congress allowed the FISA Court to approve collection of data in bulk, in addition to warrants targeted at individuals.

[11][12] In an oral history, Robertson said: In the exercise of its quotidian warrant-issuing function, the FISA Court acts like a magistrate judge.

[3] After retiring from the bench, Robertson became a mediator and arbitrator with JAMS, deciding complex commercial cases.