NEW YORK — The Colorado Supreme Court refused to reinstate Ward L. Churchill Monday as a University of Colorado professor, despite his longstanding contention that he was dismissed because of his controversial political views.

Upholding two lower-court decisions on Churchill’s case, the court affirmed that the university’s Board of Regents had essentially acted as judges in firing him for academic misconduct in 2007 and was therefore legally immune to his attempts to win his job back.

Churchill, a professor of ethnic studies, created a national uproar for describing some victims of the Sept. 11 terrorist attacks as ‘‘little Eichmanns’’ in a 2001 essay, referring to Adolf Eichmann, the Nazi who helped carry out the Holocaust. But the essay did not draw attention until 2005.

Shortly thereafter, several legal scholars came forward accusing Churchill of committing plagiarism in his research on American Indians, which eventually led to his dismissal.

He has been trying to get his job back ever since, maintaining that his political views were the real reason he was fired and accusing the university of violating his free speech rights.

‘‘The Colorado state Supreme Court spends 55 pages saying the regents are above the law,’’ said David A. Lane, Churchill’s lawyer. ‘‘Regents at universities all over the country should feel emboldened to feel free to violate the First Amendment any time they want, as long as there is some sham due process given before they do it.’’

Lane said he planned to appeal to the US Supreme Court.

The ruling, one day before the 11th anniversary of the attacks, is the culmination of years of bitter legal battles between Churchill and the school. In 2009, a Denver jury agreed with Churchill’s assertion he was wrongfully fired but awarded him only $1 in damages.

The district judge in the case, Larry J. Naves, refused to return him to the classroom, ruling that the regents’ actions were quasijudicial and legally protected.