Whether a Court of Appeals may review, on petition for a writ of mandamus, the denial of a criminal defendant's motion to dismiss the indictment on speedy-trial grounds

QUESTION PRESENTED Whether a Court of Appeals may review, on petition for a writ of mandamus, the denial of a criminal defendant’s motion to dismiss the indictment on speedy-trial grounds, or whether, as the Fifth Circuit held below, the ultimate availability of post-judgment appellate review categorically bars mandamus relief— even where, as here, the District Court concludes that a criminal defendant has suffered substantial, actual prejudice as a result of post-indictment delay in bringing him to trial. (i)