Some reliance was placed by the defendant's counsel upon the fact that the prohibition of slavery in this territory was in the words, "that slavery, &c., shall be and is hereby _forever_ prohibited." But the insertion of the word _forever_ can have no legal effect. Every enactment not expressly limited in its duration continues in force until repealed or abrogated by some competent power, and the use of the word "forever" can give to the law no more durable operation. The argument is, that Congress cannot so legislate as to bind the future States formed out of the territory, and that in this instance it has attempted to do so. Of the political reasons which may have induced the Congress to use these words, and which caused them to expect that subsequent Legislatures would conform their action to the then general opinion of the country that it ought to be permanent, this court can take no cognizance. However fit such considerations are to control the action of Congress, and however reluctant a statesman may be to disturb what has been settled, every law made by Congress may be repealed, and, saving private rights, and public rights gained by States, its repeal is subject to the absolute will of the same power which enacted it. If Congress had enacted that the crime of murder, committed in this Indian Territory, north of thirty-six degrees thirty minutes, by or on any white man, should _forever_ be punishable with death, it would seem to me an insufficient objection to an indictment, found while it was a Territory, that at some future day States might exist there, and so the law was invalid, because, by its terms, it was to continue in force forever. Such an objection rests upon a misapprehension of the province and power of courts respecting the constitutionality of laws enacted by the Legislature. If the Constitution prescribe one rule, and the law another and different rule, it is the duty of courts to declare that the Constitution, and not the law, governs the case before them for judgment. If the law include no case save those for which the Constitution has furnished a different rule, or no case which the Legislature has the power to govern, then the law can have no operation. If it includes cases which the Legislature has power to govern, and concerning which the Constitution does not prescribe a different rule, the law governs those cases, though it may, in its terms, attempt to include others, on which it cannot operate. In other words, this court cannot declare void an act of Congress which constitutionally embraces some cases, though other cases, within its terms, are beyond the control of Congress, or beyond the reach of that particular law. If, therefore, Congress had power to make a law excluding slavery from this territory while under the exclusive power of the United States, the use of the word "forever" does not invalidate the law, so long as Congress has the exclusive legislative power in the territory.