The decision by the United States Court of Appeals for the First Circuit comes as jury selection in the case has dragged on for several weeks, delayed by the weather and the tedious process of selecting potential jurors from a list of more than 1,300 who filled out questionnaires. The judge overseeing the case, George A. O’Toole Jr. of Federal District Court, has rejected three requests by Mr. Tsarnaev’s lawyers to move the trial.

The appeals court, which refused a defense request in January to intervene, scheduled arguments for next Thursday, said Susan Goldberg, the circuit executive. Until then, the court said, jury selection will continue.