[Footnote 204: _Quaestiones juris publici_, I. c. 3: "_quamvis autem nulla specialis sit commerciorum prohibitio ipsa tamen jure belli commercia sunt vetita_."] [Footnote 205: For instance, Pillet, p. 74, and Mérignhac, p. 57.] [Footnote 206: For instance, Geffcken in his note 4 to Heffter, p. 265.] These assertions are remnants of the time when the distinction[207] between International and Municipal Law was not, or not clearly, drawn. International Law, being a law for the conduct of States only and exclusively, has nothing to do directly with the conduct of private individuals, and both assertions are, therefore, nowadays untenable. Their place must be taken by the statement that, States being sovereign and the outbreak of war bringing the peaceful relations between belligerents to an end, it is within the competence of every State to enact by its Municipal Law such rules as it pleases concerning intercourse, and especially trading, between its own and enemy subjects. And if we look at the Municipal Laws of the several countries, we find that they have to be divided into two groups. To the one group belong those States--such as Austria-Hungary, Germany, Holland, and Italy--whose Governments are empowered by their Municipal Laws to prohibit by special order all trading with enemy subjects at the outbreak of war. In these countries trade with enemy subjects is permitted to continue after the outbreak of war unless special prohibitive orders are issued. To the other group belong those States--such as Great Britain, the United States of America, and, unless _desuetudo_[208] has made an alteration, France--whose Municipal Laws declare trade and intercourse with enemy subjects _ipso facto_ by the outbreak of war prohibited, but empowers the Governments to allow by special licences all or certain kinds of such trade. [Footnote 207: See above, vol. I. § 20.] [Footnote 208: See Meyer, _op. cit._ p. 91.] As regards the law of Great Britain[209] and the United States of America, it has been, since the end of the eighteenth century, an absolutely settled[210] rule of the Common Law that, certain cases excepted, all trading with alien enemies is _ipso facto_ by the outbreak of war illegal unless it is allowed by special licences of the Crown. From the general principle asserted in the leading cases,[211] the Courts have drawn the following more important consequences:-- (1) All contracts, entered into _during_ a war,[212] with alien enemies without a special licence are illegal, invalid, and can never be enforced, unless the contract was one entered into in case of necessity,[213] or in order to supply[214] an invading English army or the English fleet, or by prisoners[215] of war concerning personal services and requirements.