Mr. Messenger was raised in Cody, Wyoming. He graduated from the University of Nebraska in Lincoln with a Bachelor of Arts Degree in 1969. He graduated from the University of Wyoming College of Law with a Juris Doctorate Degree in 1975. In the interim, Mr. Messenger served in the U.S. Army in Vietnam for fourteen months in 1970 and 1971, receiving an honorable discharge and was awarded the Bronze Star Medal.
Mr. Messenger was admitted to the Wyoming State Bar and the U.S. District Court for the District of Wyoming in 1975. In 1976 he was admitted to the Tenth U.S. Circuit Court of Appeals and in 1988 he was admitted to the United States Supreme Court. He has been a member of the Shoshone and Arapaho Tribal Court since 1995.
Mr. Messenger has been active in both the Wyoming State Bar and the Wyoming Trial Lawyers Association. For the Wyoming State Bar, he served as Commissioner for the Fifth Judicial District; member of the Fee Dispute Committee and member of the Judicial Nominating Commission. He was also instrumental in the establishment of the Wyoming Lawyers Assistance Program.
From 1984 to 1985 Mr. Messenger was President of the Wyoming Trial Lawyers Association, having served on its Board of Directors from 1977 to present. In 2018, he was presented with the Lifetime Achievement Award.
Since 2002, he has received the AV Peer Review Rating from Martindale Hubbell, the nation's most prestigious attorney rating. He is currently rated AV Preeminent. The rating recognizes the highest level of professional and ethical standards in the legal profession.
He has served clients needing assistance in personal injury and wrongful death situations; water rights disputes; trust and estate litigation; commercial, agricultural, and contract disputes; and he previously litigated in the areas of workers' compensation and domestic relations. All this was in addition to practicing statewide from his office in Thermopolis, Wyoming and presently in general practice throughout the four counties comprising the Big Horn Basin in northwest Wyoming. He has also served as Thermopolis Town Attorney from 1996 to the present; and Hot Springs County and Prosecuting Attorney from 1979 to 1982. For many years he and his law firm contracted with the Wyoming Public Defenders Office and tried many criminal cases.