A contract RESTRAINT of trade is a contract by which a person agrees with the other person not to carry out any specific trade with a third person who is not a party to this contract in future. A contract in RESTRAINT of trade, in the absence of special justifying circumstances, is contrary to public order and the article 28 of the Constitution and thus not valid. A contract in RESTRAINT of trade can be valid if three conditions are satisfied: the contract must be reasonable, that is, it must be reasonable in the object of RESTRAINT and it scope must not exceed the time or area than is necessary to protect that interest. There must be a contracting interest meriting protection, that is, the interest must arise from the contractual relation between the parties and it must not be contrary to the public interest, that is, it must be useful, or at least, not cause any damage to public interests.