Not only must there be a legal object to a contract, but there must be competent parties. Competent persons are those who have the power and capacity to enter into the formation of valid contracts. Corporations may make contracts in furtherance of the purposes for which they are organized. This power need not be expressly granted. Contracts not within the scope of the purposes for which the corporation is organized are said to be "ultra vires." There is considerable difference of opinion over the question of how far such contracts will be enforced, when they have been partly performed. Aliens may generally contract the same as citizens; contracts with alien enemies are, as a rule, absolutely void. As regards other persons there are generally two restrictions, (1) persons lacking mental capacity; (2) persons lacking legal capacity, though they may have mental capacity. Persons lacking mental capacity are lunatics, idiots and drunkards. Contracts with such persons, except for necessaries furnished in good faith and under justifiable circumstances, are either voidable or void. To be able to escape a contract made while under the influence of liquor, a person must have been so much intoxicated as to have been unable to understand and appreciate the nature of his acts. Insane persons, provided they recover their reason, may ratify contracts made while in their former condition. Persons lacking legal capacity to contract are infants and, in some jurisdictions, married women. Infants are persons under twenty-one years of age. In many States women become of age when eighteen, and in some prior to that time if married. Contracts made during infancy are voidable and not void - that is, they may be evaded by the infant but not by the other person, who is not allowed to plead the infancy of the former as a reason for not fulfilling his part of the agreement. They may be avoided by the infant even after he becomes of age. Infants, however, are liable for necessaries furnished them - but only for their fair value. Necessaries include not only the bare necessities of life but those things necessary to the infant to maintain his station in life. To recover against an infant the plaintiff must show (1) that the articles were in fact necessaries; (2) that the infant was not already supplied with them; (3) their reasonable market value. When an infant repudiates a contract he must repudiate the whole contract; he cannot accept one part and escape the rest. Infants are liable upon contracts that they ratify. Ratification occurs when, after becoming of age, the infant either promises to perform what he has agreed to do, or does some act from which such promise can be implied. Under the old common law married women could not contract at all; all contracts made by them were absolutely void. Modern legislation, however, has greatly enlarged everywhere their power and capacity to contract. In general a married woman may now contract as fully as a single woman, and may sue and be sued apart from her husband.