Without the aid of the courts, Congress is no match for the Executive. Presidents decide, period. Congress, outgunned by the Executive and deserted by the Judiciary, goes along. The Framers would have been dismayed.
Thus the Supreme Court’s solution to the problem here was to rely on Congressional authorization of war as a sufficient substitute for Congressional declaration of war. The Court never directly addressed the ship-owner’s point that the Constitution speaks only of declarations of war, not of authorizations. The Framers would have been spinning in their graves.