Harper's forebears include David Rowe, an Assistant Principal Chief of the Cherokee Nation who was elected as a judge of the Northern Judicial Circuit shortly after the Civil War.

[7][3][2] He is most known for his work in the Cobell v. Kempthorne, a large class-action lawsuit brought by Native American representatives against two departments of the United States government.

[2] He then became a partner at Kilpatrick Townsend & Stockton, in Washington, D.C., where he focused his practice on litigation and Native American affairs, representing tribes and individual Indians.

[14] Haaland ran in New Mexico's first congressional district and won, becoming one of the two first Native American woman elected to Congress, alongside Sharice Davids.

[12][8] Many human rights advocates were unfamiliar with Harper, and as such the pick reflected a long-standing practice of presidents rewarding top supporters with ambassadorships and similar postings.

"[16] Senator Jon Tester of Montana said, on the other hand, that "As a longtime advocate for the civil rights of Native Americans, Keith will be a great Ambassador for our country.

[15] Eventually, Harper was confirmed by the United States Senate on June 3, 2014, nearly a year after his nomination, in a party-line 52–42 vote with Democrats supporting and Republicans opposed.

[15] Harper thus became the first person from a federally recognized Native American tribe to achieve the rank of U.S. ambassador to the United Nations Human Rights Council.

[4] In February 2017, Harper returned to practice as a partner at Kilpatrick Townsend & Stockton,[18] in Washington, D.C., on Native American affairs and international matters.