The court adjudges, I think erroneously, that Congress is without power, under either the Thirteenth or Fourteenth Amendments, to establish such regulations, and that the first and second sections of the statute are, in all their parts, unconstitutional and void. Whether the legislative department of the government has transcended the limits of its constitutional powers, “is at all times,” said the court in _Fletcher ~v.~ Peck_, 6 Cr. 128, “a question of much delicacy, which ought seldom, if ever, to be decided in the affirmative, in a doubtful case.... The opposition between the Constitution and the law should be such that the judge feels a clear and strong conviction of their incompatibility with each other.” More recently in _Sinking Fund Cases_, 99 U. S., 718, we said: “It is our duty when required in the regular course of judicial proceedings, to declare an Act of Congress void if not within the legislative power of the United States; but this declaration should never be made except in a clear case. Every possible presumption is in favor of the validity of a statute, and this continues until the contrary is shown beyond a rational doubt. One branch of the government cannot encroach on the domain of another without danger. The safety of our institutions depends in no small degree on a strict observance of this salutary rule.” Before considering the language and scope of these amendments, it will be proper to recall the relations subsisting, prior to their adoption, between the national government and the institution of slavery, as indicated by the provisions of the Constitution, the legislation of Congress, and the decisions of this court. In this mode we may obtain keys with which to open the mind of the people, and discover the thought intended to be expressed. In section 2 of article IV. of the Constitution it was provided that “no person held to service or labor in one State, under the laws thereof, escaping into another, shall, in consequence of any law or regulation therein, be discharged from such service or labor, but shall be delivered up on claim of the party to whom such service or labor may be due.” Under authority of this clause Congress passed the Fugitive Slave Law of 1793, establishing a mode for the recovery of fugitive slaves, and prescribing a penalty against any person who should knowingly and willingly obstruct or hinder the master, his agent, or attorney, in seizing, and recovering the fugitive, or who should rescue the fugitive from him, or who should harbor or conceal the slave after notice that he was a fugitive. In _Prigg ~v.~ Commonwealth of Pennsylvania_, 16 Pet. 539, this court had occasion to define the powers and duties of Congress in reference to fugitives from labor. Speaking by MR. JUSTICE STORY, it laid down these propositions: