Born in Bonners Ferry, Idaho, and raised in Lewiston, McNichols served in the United States Navy during World War II, from 1942 to 1947, under Raymond A. Spruance[citation needed].
[1][2] On April 15, 1964, McNichols was nominated by President Lyndon B. Johnson to a seat on the United States District Court for the District of Idaho vacated by the retirement of Judge Chase A.
[3] He was confirmed by the United States Senate on April 30 and received his commission on May 1, 1964.
[5][6] During Robert's investiture to the federal bench in January 1980, the elder brother swore the younger in.
[8] He and his wife, Mary Kay Riley McNichols (1914–1991), are buried at Morris Hill Cemetery in Boise.