Lindsey Halligan, a close ally of U.S. President Donald Trump, went before a grand jury in late September seeking criminal charges against a high-profile target: former FBI Director James Comey.

Halligan had been appointed interim U.S. attorney for the Eastern District of Virginia only a few days prior after Trump publicly vented frustration with the lack of action against some of his top antagonists. She had no experience as a prosecutor and appeared before the grand jury alone after career staff in her office declined to sign on to the case. She secured an indictment against Comey, but the case almost immediately ran into problems. Judges began tallying a cascade of legal errors that culminated on Monday with the dismissal of the charges against Comey and a second prosecution against New York Attorney General Letitia James, another top Trump target.

The ruling from U.S. District Judge Cameron McGowan Currie was based on a procedural issue: that Halligan¡¯s appointment violated a federal law limiting the tenures of interim U.S. attorneys. But it underscored growing pushback in the courts to Trump¡¯s demands that the Justice Department use its vast authority to pursue retribution against people who have criticized or investigated the president.