From 1991 to 1994, Contreras was an associate at
Jones Day. In 1994 he was a government attorney in the
District of Columbia. From 1994 to 2012, he served as an
assistant United States attorney, in the District of Columbia from 1994 to 2003 and in the District of Delaware and as chief of the civil division from 2003 to 2006. He returned as an AUSA to the District of Columbia from 2006 to 2012, serving concurrently as chief of the civil division. In April 2016 Chief Justice
John Roberts appointed Contreras to the
United States Foreign Intelligence Surveillance Court for a term starting May 19, 2016.
Notable cases On November 17, 2016, Contreras dismissed a lawsuit against
U.S. Senate Majority Leader Mitch McConnell seeking to compel a vote on the
U.S. Supreme Court nomination of
Merrick Garland, finding that the plaintiff, who had simply said he was a voter, had no
standing to sue. In 2017, Contreras was assigned the case of
United States of America v. Michael T. Flynn, the former
National Security Adviser to President
Donald Trump. The two-page indictment was released on December 1, 2017. Contreras accepted Flynn's guilty plea to one count of
making false statements to the FBI in the course of their investigation into
Russian interference in the 2016 U.S. presidential election. The guilty plea was part of a plea bargain with the
Special Counsel investigation led by
Robert S. Mueller III. The case was reassigned to District Judge
Emmet G. Sullivan. According to several reputable sources, text messages show that
Peter Strzok, a veteran FBI counterintelligence official who worked on the Flynn case as part of Mueller's team, knew Contreras. On August 6, 2020, Contreras dismissed a lawsuit House Republicans filed against
U.S. House Speaker Nancy Pelosi that challenged
proxy voting rules adopted during the 2020
COVID-19 pandemic. He ruled that the Constitution's "
Speech or Debate Clause" prohibited lawsuits over Congress's legislative efforts, concluding, "the Court can conceive of few other actions, besides actually debating, speaking, or voting, that could more accurately be described as 'legislative' than the regulation of how votes may be cast". On March 5, 2021, Contreras ruled that the states of
Illinois,
Nevada, and
Virginia had ratified the
Equal Rights Amendment too late for the amendment to be valid, as they did so after the congressionally imposed 1982 deadline. On March 4, 2025, Contreras ruled that President
Donald Trump had unlawfully terminated
Merit Systems Protection Board Chair Cathy Harris. Harris had been dismissed via a two-sentence email on February 10, 2025, with no reason given. Contreras found that under the
Civil Service Reform Act of 1978, MSPB members can be removed only for "inefficiency, neglect of duty, or malfeasance in office", and ordered Harris reinstated. Citing the 1935 Supreme Court precedent ''
Humphrey's Executor v. United States'', he wrote that "direct political control over the MSPB would neuter the Civil Service Reform Act's statutory scheme." The
Justice Department immediately appealed, and on March 28, 2025, the
D.C. Circuit granted an emergency stay, effectively allowing Trump to remove Harris while the case continued. On May 29, 2025, Contreras ruled that Trump's tariffs imposed under the
International Emergency Economic Powers Act (IEEPA) were unlawful. In
Learning Resources, Inc. v. Trump, two Illinois-based toy manufacturers challenged Trump's tariffs on imports from China, Canada, Mexico, and other countries. Contreras found that IEEPA "does not authorize the president to impose the tariffs set forth" in Trump's executive orders, writing, "the power to regulate is not the power to tax". Unlike the
Court of International Trade, which issued a nationwide injunction the previous day, Contreras's order applied only to the two plaintiffs. The case was consolidated with others, and on February 20, 2026, the Supreme Court ruled that the IEEPA tariffs were unlawful. ==See also==