"The true reasons of the distinction upon which the judgments in these case of voluntary restraints are founded, are, first, the mischief which may arise from them, 1st, to the party, by the loss of his livelihood, and the subsistence of his family; 2d to the publick, by depriving it of an useful member.
" Another reason is, the great abuses these voluntary restraints are liable to; as for instance, from corporations, who are perpetually labouring for exclusive advantages in trade, and to reduce it into as few hands as possible; as likewise from masters, who are apt to give their apprentices much vexation on this account, and to use many indirect practices to procure such bonds from them, lest they should prejudice them in their custom, when they come to set up for themselves.
" 3dly, because in a great many instances, they can be of no use to the obligee; which holds in all cases of general restraint throughout England; for what does it signify to a tradesman in London, what another does at Newcastle? and surely it would be unreasonable to fix a certain loss on one side, without any benefit to the other." 40
37 See to similar effect Colgate v. Bacheler, 2 Gro. Eliz. 872.
38 Rogers o. Parry, 2 Bulstr. 136; Jelliet v. Broad, Noy. 98; Broad v. Jollyfe, Cro. Jac. 596. See also Prugnell v. Gosse, Aleyn, 67; Clerk v. Governer & Taylors of Exeter, 3 Lev. 641.
39 1 Peere Wms. 181.
In the further development of the subject the emphasis thrown on these reasons has varied, and has differed somewhat in England and in the United States. With the greater ease of changing occupations in modern life, less weight is attached to the reason that the promisor will be rendered a charge upon the community and himself suffer undue hardship. This rear son is, moreover, wholly inapplicable where the promisor is a corporation. The modern English law has thrown the emphasis almost entirely upon the impropriety of requiring a promise greater in extent than is required for the needs of the promisee, since thereby the promisor would be injured without any corresponding advantage to the promisee. The American law, on the other hand, has been chiefly concerned with the injury to the public; - not that arising indirectly from the injury to the promisor, but that arising from lack of competition, with the consequent tendency to at least a partial monopoly owing to the withdrawal of the promisor from the field. Though emphasis thus varies, it is true in the United States, as well as in England, that a covenant exceeding the reasonable requirements of the promisee may be unlawful for that reason alone.41 If the agreement affects interstate trade or commerce, its validity will be judged by Federal law and not by that of the State where the contract was made.42