Neither of these propositions was questioned in the case of _Hepburn_ v. _Griswold_. The judges who dissented in that case maintained that the clause in the act of February 25th, 1862, making the United States notes a legal tender in payment of debts, was an appropriate, plainly adapted means to a constitutional end, not prohibited but consistent with the letter and spirit of the constitution. The majority of the court as then constituted, five judges out of eight, felt "obliged to conclude that an act making mere promises to pay dollars a legal tender in payments of debts previously contracted is not a means appropriate, plainly adapted, really calculated to carry into effect any express power vested in congress, is inconsistent with the spirit of the constitution, and is prohibited by the constitution." In the case of the _United States_ v. _De Witt_, we held unanimously that a provision of the internal revenue law prohibiting the sale of certain illuminating oil in the states was unconstitutional, though it might increase the production and sale of other oils, and consequently the revenue derived from them, because this consequence was too remote and uncertain to warrant the court in saying that the prohibition was an appropriate and plainly adapted means for carrying into execution the power to lay and collect taxes. We agree, then, that the question whether a law is a necessary and proper means to execution of an express power, within the meaning of these words as defined by the rule--that is to say, a means appropriate, plainly adapted, not prohibited but consistent with the letter and spirit of the constitution--is a judicial question. Congress may not adopt any means for the execution of an express power that congress may see fit to adopt. It must be a necessary and proper means within the fair meaning of the rule. If not such it cannot be employed consistently with the constitution. Whether the means actually employed in a given case are such or not the court must decide. The court must judge of the fact, congress of the degree of necessity.