This power has been held by the supreme court to be an exclusive one in the general government--and one that cannot be controlled by the states. Yet it gives congress no constitutional authority to legalize any commerce inconsistent with natural justice between man and man; although the _mere_ verbal import of the words, if stretched to their utmost tension in favor of the wrong, would authorize congress to legalize a commerce in poisons and deadly weapons, for the express purpose of having them used in a manner inconsistent with natural right--as for the purposes of murder. At natural law, and on principles of natural right, a person, who should _sell_ to another a weapon or a poison, knowing that it would, or intending that it should be used for the purpose of murder, would be legally an accessary to the murder that should be committed with it. And if the grant to congress of a "power to regulate commerce," can be stretched beyond the _innocent_ meaning of the words--beyond the power of regulating and authorizing a commerce that is consistent with natural justice--and be made to cover every thing, intrinsically criminal, that can be perpetrated under the name of commerce--then congress have the authority of the constitution for granting to individuals the liberty of bringing weapons and poisons from "foreign nations" into this, and from one state into another, and selling them openly for the express purposes of murder, without any liability to legal restraint or punishment. Can any stronger cases than these be required to prove the necessity, the soundness, and the inflexibility of that rule of law, which requires the judiciary to ascribe an innocent meaning to all language that will possibly bear an innocent meaning? and to ascribe _only_ an innocent meaning to language whose mere verbal import might be susceptible of both an innocent _and_ criminal meaning? If this rule of interpretation could be departed from, there is hardly a power granted to congress, that might not _lawfully_ be perverted into an authority for legalizing crimes of the highest grade. In the light of these principles, then, let us examine those clauses of the constitution, that are relied on as recognizing and sanctioning slavery. They are but three in number. The one most frequently quoted is the third clause of Art. 4, Sec. 2, in these words: "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." There are several reasons why this clause renders no sanction to slavery. 1. It must be construed, if possible, as sanctioning nothing contrary to natural right.