24. It is a presumption of law, necessary in the conduct of government, that all acts of Congress are constitutional until pronounced unconstitutional by a competent judicial tribunal. An issue arising between parties involves a law. In deciding the issue the tribunal decides as to the constitutionality of the law, provided its constitutionality forms part of the issue. Unless the issue of the constitutionality arises and is before the tribunal, that body can make no decision respecting the constitutionality of the law. Thus whether or not the powers exercised by Congress, as expressed in a piece of legislation—exceed the powers granted to it by the Constitution is a question which Congress itself is powerless to decide. The Constitution itself does not so declare; on the other hand it does not provide that Congress shall be the final judge of its own powers. The principle regulative of the exercise by Congress of powers delegated to it is laid down by the Supreme Court:[59] “Let the end be legitimate, let it be within the scope of the Constitution, and all means which are appropriate, which are plainly adapted to that end, which are not prohibited, but consist with the letter and spirit of the Constitution, are constitutional.” CHAPTER III THE LAW OF LEGISLATIVE POWERS (II) 25. The powers of Congress, whether expressed or implied, are powers incident to sovereignty, being essential to the existence of the government which sovereignty has created. The principle is laid down in _The Federalist_, that the government of the Union “must possess all the means and have a right to resort to all the methods of executing the powers with which it is intrusted.”[60] The immediate comparison here is between the government of the United States and those of the States. The federal government must possess powers as adequate for its purposes as are the powers possessed and exercised by the particular States. The principle is laid down by Hamilton yet more explicitly: A government ought to contain in itself every power requisite to the full accomplishment of the objects committed to its care, and to the complete execution of the trusts for which it is responsible, free from every other control but a regard for the public good and to the sense of the people.[61]