I agree that there is still left, under the license and protection of the law of nations, the prosecution of hostilities on the high seas by privateers and private armed vessels. And I agree that, although the crime proved in this case does come within the description and punishment of robbery and piracy, in its own actual traits and features, yet if it be shown that what is thus made piracy and robbery by the statute was actually perpetrated by a privateer, under the protection of the law of nations, with a commission from a sovereign nation, within the scope of the authority of that commission, it is an answer to an indictment, the terms of which had been otherwise proved. And that is undoubtedly what is claimed here. You have proved piracy and robbery under the eighth section, say these defendants, if we cannot impart to the circumstances and features of this crime some public quality and authority which saves the transaction from condemnation and punishment. _Mr. Brady_: We say no such thing. We say that, if they acted in good faith, however mistaken, and though the commission may be void, they have not committed any offence whatever. _Mr. Evarts_: This is the extent of my concession, as matter of law,--that it is an answer to a charge of piracy which is otherwise complete, that the crime was committed under conditions which, by the law of nations, relieve it from punishment. Now, what are the conditions that the law of nations requires? First, there must be a war. We do not allow private armed vessels to prosecute general marauding hostilities in support of the views of their Governments. We do not allow the interruption of the freedom of the seas by such marauding vessels, except in cases of flagrant war, which neutral nations are compelled to recognize. Secondly. The privateer must have received its commission from a public, national, sovereign power. You cannot make a privateer, and turn private acts that, by the law of nations and by municipal law, are piratical, into acts of war, which are of the same intrinsic quality and have the force of national acts, unless by this _sine qua non_ of public authority and adoption.