Can a court really "strike down" a statute, as we so often casually say when discussing a constitutional case? No, not really. Repeal of a statute is a legislative function. The theory of judicial review, as explained way back in Marbury v. Madison, is that the court must decide the case, and if the higher law of the Constitution points to one result and the lower law of the statute points to the other, the higher law must govern. That does not wipe the statute off the books, though. The statute at issue in Marbury gave the Supreme Court the authority to issue writs of mandamus, and it still had that authority under that statute after Marbury as long as it exercised the authority in its appellate jurisdiction, such as issuing it to control a lower court, and not by expanding its original jurisdiction beyond constitutional limits.
But can a court decide that a statute is completely void?