A federal appeals court on Thursday barred federal prosecutors in Maryland from continuing to directly review thousands of files obtained from a search warrant executed in June at a Baltimore law firm.

The case in the U.S. Court of Appeals for the Fourth Circuit, which heard arguments Tuesday, is unfolding largely under a seal that shields the names of the law firm, and lawyers, who were subject to the search warrant. The Baltimore Sun identified the targets of the obstruction investigation as two criminal defense lawyers.