Colorado’s federal trial court took the unusual step last week of appointing Peter McNeilly as the state’s top federal prosecutor, who may hold that position until a presidentially nominated and U.S. Senate-confirmed appointee takes over.

In a single-sentence order on Oct. 1, U.S. District Court Chief Judge Philip A. Brimmer indicated McNeilly will be Colorado’s U.S. attorney effective Oct. 14. According to the clerk, the court has not exercised its power to make an appointment under federal law since 2018. At that time, during the first Trump administration, the court appointed Robert C. Troyer until the Senate confirmed President Donald Trump’s nominee, Jason R. Dunn.

A somewhat complex set of rules governs how vacancies may be filled for positions that are subject to Senate confirmation.

An “acting” U.S. attorney can serve for up to 300 days under certain circumstances, with specific positions designated as eligible for the acting role. The U.S. attorney general may also appoint a U.S. attorney to serve for up to 120 days. If that appointee hits the 120-day limit, then the federal district court may appoint someone to the position until there is a Senate-confirmed appointee.

In Colorado’s case, J. Bishop Grewell became the acting U.S. attorney in January. Then, on June 16, Attorney General Pamela Bondi appointed McNeilly. The district court’s continuation of McNeilly’s appointment becomes effective at the 120-day mark.

McNeilly has been an assistant U.S. attorney in Colorado since 2014. He has focused on drug-related cases and violent crime. McNeilly is also a lieutenant colonel in the U.S. Marine Corps who served as a military prosecutor, legal advisor and judge.

“Peter is a well-respected attorney who represented the government very ably when I was on the bench,” said former U.S. Magistrate Judge Kristen L. Mix, who retired in 2023.

Colorado’s U.S. Attorney’s Office did not respond to a question about the appointment process. The office’s role is to prosecute federal criminal cases and to represent the government in civil litigation.

Elsewhere across the country, courts have found some of the Trump administration’s appointed, but not Senate-confirmed, U.S. attorneys to be unlawfully occupying their positions. Last week, a judge disqualified Nevada’s U.S. attorney for circumventing the time limit. In July, New Jersey’s district judges declined to continue the appointment of Trump’s former personal attorney after she reached her 120-day limit, prompting Bondi to retaliate against the judges’ appointed U.S. attorney.

That same month, the judges from the Northern District of New York declined to continue the appointment of that jurisdiction’s U.S. attorney, but they also did not appoint someone else for the role.