Chief Justice Mike McGrath was raised in Butte, Montana.  He earned a degree in business administration from the University of Montana in 1970 and graduated from  Gonzaga University School of Law in 1975. Following graduation from law school he worked as a Reginald Heber Smith Community lawyer fellow in Reno, Nevada, providing legal services to low-income clients.

He served in the United States Air Force from 1970 until an honorable discharge in 1972.

He was a Montana Assistant Attorney General from 1977 to 1982. He was elected to five terms as Lewis and Clark County Attorney beginning in 1983.  He was elected to two terms as Montana Attorney General.  As Attorney General he served from 2000 to 2008, oversaw a staff of more than 700 employees and focused on methamphetamine prevention and natural resource and land issues.

Mike McGrath was elected to an eight-year term as Chief Justice of the Montana Supreme Court in November, 2008, and took office January 5, 2009.