According to the will theory of contract, which was dominant in the 19th century and still exerts a strong influence, a contract is not presumed valid unless all parties agree to it voluntarily, either tacitly or explicitly, without coercion. Lysander Spooner, a 19th century lawyer and staunch supporter of a right of contract between individuals, in his essay No Treason, argues that a supposed social contract (of the Rousseauean sort) cannot be used to justify governmental actions such as taxation, because government will initiate force against anyone who does not wish to enter into such a contract. As a result, he maintains that such an agreement is not voluntary and therefore cannot be considered a legitimate contract at all. However, the philosophical concept of social contract does not address the same issues as present-day juridical contract theory, making the name "social contract" potentially misleading. For this reason some thinkers, such as James Madison, preferred the term social compact. The key notion of social contract or compact is that the individual consents by entering or remaining on the dominion of an existing society, which is usually a geographic territory, in much the same way one does when entering or remaining in someone's household or private property. People are normally brought up from childhood to respect the boundaries of societies, including families, and the rules made by them for their territorial spaces. That is part of the socialization development process.
As legal scholar Randy Barnett has argued, however, while presence in the territory of a society is necessary for consent, it is not consent to any rules the society might make, and a second condition of consent is that the rules be consistent with underlying principles of justice and the protection of natural and social rights, and have procedures for effective protection of those rights (or liberties). This has also been discussed by O.A. Brownson, who argued that there are, in a sense, three "constitutions" involved: The first the constitution of nature that includes all of what the Founders called "natural law". The second would be the constitution of society, an unwritten and commonly understood set of rules for the society formed by a social contract before it establishes a government, by which it does establish the third, a constitution of government. To consent, a necessary condition is that the rules be constitutional in that sense.
Modern Anglo-American law, like European civil law, is based on a will theory of contract, according to which all terms of a contract are binding on the parties because they chose those terms for themselves. This was less true when Hobbes wrote Leviathan; then, more importance was attached to consideration, meaning a mutual exchange of benefits necessary to the formation of a valid contract, and most contracts had implicit terms that arose from the nature of the contractual relationship rather than from the choices made by the parties. Accordingly, it has been argued that social contract theory is more consistent with the contract law of the time of Hobbes and Locke than with the contract law of our time, and that features in the social contract which seem anomalous to us, such as the belief that we are bound by a contract formulated by our distant ancestors, would not have seemed as strange to Hobbes' contemporaries as they do to us.