One of the oldest public policies evolved by courts is the common-law prohibition against restraint of trade. From the early days of industrialism, the courts took a dim view of ostensible competitors who agreed among themselves to fix prices or not to sell in each other’s territories. Since 1890, with the enactment of the Sherman Act, the law of restraint of trade has been absorbed by federal and state antitrust statutes. But the common-law prohibition still exists. Though today it is concerned almost exclusively with promises not to compete in sales of businesses and employment contracts, it can arise in other settings. For example, George’s promise to Arthur never to sell the parcel of land that Arthur is selling to him is void because it unreasonably restrains trade in the land.
The general rule is one of reason: not every restraint of trade is unlawful; only unreasonable ones are. As the Restatement puts it, “Every promise that relates to business dealings or to a professional or other gainful occupation operates as a restraint in the sense that it restricts the promisor’s future activity. Such a promise is not, however, unenforceable, unless the restraint that it imposes is unreasonably detrimental to the smooth operation of a freely competitive private economy.” 1 An agreement that restrains trade will be construed as unreasonable unless it is ancillary to a legitimate business interest and is no greater than necessary to protect the legitimate interest. Restraint-of-trade cases usually arise in two settings: (1) the sale of a business and an attendant agreement not to compete with the purchasers and (2) an employee’s agreement not to compete with the employer should the employee leave for any reason.