[3] During his time with the DOJ, Simon also served in 1985 as a special assistant United States attorney for the Eastern District of Virginia.

[3][5] On July 14, 2010, President Barack Obama nominated Simon to a seat on the United States District Court for the District of Oregon to fill the seat vacated by Judge Ancer L. Haggerty, who assumed senior status in August 2009.

[8] In his committee questionnaire, Simon encountered questions from Republican senators about his past work as a volunteer lawyer for the American Civil Liberties Union.

[5] On November 2, 2019, Simon issued a temporary restraining order against a Trump administration rule requiring immigrants prove they will have health insurance.

[11] On July 23, 2020, Simon issued a temporary restraining order preventing federal agents from using force against journalists and legal observers during the George Floyd protests in Portland, Oregon.