Comey and James Challenge Appointment of Lindsey Halligan, Trump Loyalist Prosecuting Them

A federal judge is poised to hear arguments on Thursday about whether the U.S. attorney handpicked by President Trump to prosecute two of his most prominent political opponents was lawfully appointed to her job — a question that could have serious consequences for the cases.

The arguments are set to take place at a high-stakes hearing in Federal District Court in Alexandria, Va., where prosecutors and defense lawyers will square off over whether the U.S. attorney for the Eastern District of Virginia, Lindsey Halligan, was in her post legally when she obtained indictments against James B. Comey, the former F.B.I. director, and Letitia James, the New York attorney general.

The cases are playing out separately, but lawyers for Mr. Comey and Ms. James have joined forces to ask the judge, Cameron McGowan Currie, to throw out both sets of charges if she determines that Ms. Halligan was improperly installed at Mr. Trump’s direct command in September.

The lawyers say this drastic step is needed because, in a highly unusual move, Ms. Halligan secured the indictments personally — after none of her subordinates would do so — and was the only person to sign the charging documents.

“When Ms. Halligan presented Mr. Comey’s indictment to the grand jury — just days before the statute of limitations expired — she purported to hold the mantle of U.S. attorney,” lawyers wrote in court papers this week. “But in fact, she was no different than a private citizen.”

Judge Currie has signaled she is interested in precisely that issue. And last week, she ordered the prosecutors handling both cases to provide her with a complete set of documents related to Ms. Halligan’s grand jury presentations.

The prosecutors in Mr. Comey’s case initially turned over only the transcript of an F.B.I. agent who testified to the grand jury, neglecting to hand over the transcript of Ms. Halligan’s remarks. Ultimately, the prosecutors corrected their error, blaming the mistake on the service that had transcribed the grand jury proceedings.

Judge Currie, an appointee of President Bill Clinton who normally sits in South Carolina, was assigned to the cases after all of the local federal judges were forced to step back to avoid any appearance of conflict in deciding on the appointment of the U.S. attorney they routinely deal with.

Other federal judges have already ruled that Mr. Trump’s Justice Department unlawfully used arcane procedural maneuvers to put loyalists in place atop three other U.S. attorney’s offices. Those include Alina Habba, who was put in charge of the U.S. attorney’s office in New Jersey; Sigal Chattah, who was named the acting U.S. attorney for Nevada; and Bilal Essayli, whom Mr. Trump put in the top job at the U.S. attorney’s office in the Central District of California.

In many ways, however, the legal battle over Ms. Halligan, who served as both a White House aide and a personal lawyer to Mr. Trump before taking control of the federal prosecutors’ office in Virginia, is unique.

First, none of the other U.S. attorneys found by the courts to have been improperly appointed have handled the sort of high-profile, politicized prosecutions like the ones Ms. Halligan has brought against Mr. Comey and Ms. James.

Moreover, none of the others were as personally involved in the grand jury process as Ms. Halligan was. They also did not put themselves in the potentially vulnerable position of having been the only prosecutor to have formally signed indictments like Ms. Halligan did.

Ms. Halligan’s involvement in the cases against Mr. Comey and Ms. James has been extraordinary from the start, reflecting the ways in which Mr. Trump has trampled over the longstanding tradition of the White House’s keeping distance from the affairs of the Justice Department.

He put her in charge of the U.S. attorney’s office in the Eastern District of Virginia — a critical outpost known for handling terrorism and national security matters — with explicit public instructions to go after Mr. Comey and Ms. James and despite the fact that she had never worked on a criminal prosecution.

Moreover, he cleared a path for her by ousting her predecessor, Erik S. Siebert, a career prosecutor who had refused to indict Mr. Comey out of concerns that there was insufficient evidence.

Lawyers for Mr. Comey and Ms. James have argued that Mr. Siebert himself served a 120-day stint as interim U.S. attorney — the maximum permitted under the law. Because of that, they have claimed Ms. Halligan should not be allowed to serve her own 120-day term.

“If the attorney general could make back-to-back sequential appointments of interim U.S. attorneys,” the lawyers wrote, “the 120-day period would be rendered meaningless, and the attorney general could indefinitely evade the alternate procedures that Congress mandated.”

Federal prosecutors working under Ms. Halligan have pointed to a small, procedural wrinkle. They reminded Judge Currie that when Mr. Siebert’s interim position came to an end, the judges in the Eastern District of Virginia used their own authority to reappoint him. That intervening development, prosecutors say, should allow Ms. Halligan to also serve a four-month stint as the interim U.S. attorney.

Just to be sure, however, Attorney General Pam Bondi sought last week to create a kind of fail-safe.

In an unorthodox sworn statement, Ms. Bondi said that for “the avoidance of doubt” she had retroactively named Ms. Halligan to a second post — that of special attorney — with the authority to handle the prosecutions of both Mr. Comey and Ms. James.