John E. Cassinat was born in Nebraska in 1958, and grew up in Wyoming. He spent much of his youth at work on his grandfather’s sheep and cattle ranch in Saratoga, Wyoming.
Cassinat graduated from the University of Wyoming in 1984 with a Bachelor of Science degree in Industrial Management, and from the University of California at Davis with Juris Doctorate degree in 1987. Cassinat was on active duty in the United States Marine Corps from 1988 to 1991 as a Judge Advocate and he achieved the rank of captain before his honorable discharge. While on active duty, Cassinat also went to night school at the University of San Diego and graduated in 1991 with a Master of Laws degree in taxation. He then began his 35-year career as a civil trial attorney in Sacramento California. For most of his 35-year legal career, Cassinat was the sole owner and president of Cassinat Law Corporation.
Cassinat is a life-long member of The Church of Jesus Christ of Latter-day Saints. He served a full-time mission in the Netherlands Amsterdam Mission from 1978 to 1980. He has served in many callings in the Church, including Elders Quorum President, Bishop, Stake High Councilman, and Stake President. He also taught early morning seminary and institute of religion courses for more than 10 years.
Cassinat married Jan Lester of Evanston, Wyoming in 1984. They have seven children and a growing number of grandchildren.