Thomson was born and raised in Santa Fe, New Mexico.
After graduating law school, he worked as a sole practitioner in Santa Fe and clerked under Judge Bruce D. Black of the United States District Court for the District of New Mexico.
[3][4] Thomson was appointed to the District Court by Governor Bill Richardson.
[4] In December 2018, Thomson was one of fourteen applicants who applied for two upcoming vacancies on the New Mexico Supreme Court.
[7] On January 25, 2019, Governor Michelle Lujan Grisham announced her selection of Thomson to fill the vacancy left by the retirement of Petra Jimenez Maes.