During his time on active duty, he prosecuted and defended a variety of complex cases and earned two Bronze Stars and a Meritorious Service Medal.

On September 22, 2017, President Donald Trump nominated Kees to be the United States Attorney for the Western District of Arkansas.

[2] On December 20, 2017, his nomination was confirmed in the United States Senate by voice vote.

[9][10] In June 2023, Arkansas Attorney General Tim Griffin appointed Kees to the state's Judicial Discipline and Disability Commission, an agency that investigates judges for violations of the state's judicial code of conduct.

[11] In May 2024, Kees resigned from the commission after an investigative journalist for The Intercept began making inquiries related to a report released by the Department of Justice, alleging that while serving as US Attorney Kees had an improper relationship with a subordinate and tried to block the firing of another employee who had committed "additional acts of misconduct" to try to keep his own misconduct out of the spotlight.