WASHINGTON — The Trump administration asked a federal appeals court Tuesday to reinstate Lindsey Halligan as interim U.S. attorney for the Eastern District of Virginia, arguing that her appointment was valid and that criminal cases she brought against former FBI Director James Comey and New York Attorney General Letitia James should proceed. A three-judge panel of the 4th U.S. Circuit Court of Appeals did not signal how it would rule. But Judge Albert Diaz, an Obama appointee, repeatedly pressed the administration’s attorney, Henry Whitaker, about the limits of the appointment process and the potential for presidents to bypass the Senate’s confirmation role. A federal judge ruled in November that Halligan had been improperly appointed and barred her from serving as the district’s interim U.S. attorney. The judge also dismissed indictments against Comey and James, both longtime political targets of President Donald Trump. The administration’s appeal centers on whether federal law allowed Halligan to hold the temporary position and exercise the powers of a U.S. attorney. Whitaker argued that she was legally serving when the indictments were issued. Diaz questioned whether that interpretation could allow an administration to repeatedly install interim prosecutors, effectively keeping the courts and the Senate from exercising their oversight responsibilities. When Whitaker acknowledged that a president acting in bad faith could use the process that way, Diaz responded that the possibility was the central concern. Trump-appointed Judge Julius Richardson took a different view during parts of the hearing, suggesting that Congress could amend the law if it believed the appointment authority was being abused. The case is part of a broader legal fight over the Trump administration’s use of temporary U.S. attorneys. Other federal appeals courts have upheld challenges to similar appointments, including the disqualification of Alina Habba in New Jersey. The ruling will affect not only Halligan’s status but also the future of the high-profile prosecutions against Comey and James. More broadly, the case could clarify how far an administration may go in filling top federal prosecutor positions without Senate confirmation — a question with implications for the independence and accountability of the Justice Department.