Русско-англо-русский юридический словарь

A default rule is one that governs unless the parties contract out of it. In contrast, a mandatory rule is one that governs despite a contract term to the contrary, that is, a rule that cannot be avoided by contract. One can identify which laws are default and which are mandatory by examining the sorts of contract terms that are, and are not, enforceable. For example, the legal rule that the place for delivery in a sale of goods is the seller's place of business is a default rule because parties can make an enforceable contract requiring delivery at some other location. In contrast, the legal rule giving a consumer the right that goods purchased not be "in a defective condition unreasonably dangerous to the user" is mandatory because it applies no matter what the contract terms say. The distinction between mandatory and default rules is fundamentally important because it reveals the extent of contractual freedom. Mandatory rules limit the freedom of contract, while default rules permit it. (Arbitration Law in America: A Critical Assessment edited by Edward Brunet)

A default rule is one that governs unless the parties contract out of it. In contrast, a mandatory rule is one that governs despite a contract term to the contrary, that is, a rule that cannot be avoided by contract. One can identify which laws are default and which are mandatory by examining the sorts of contract terms that are, and are not, enforceable. For example, the legal rule that the place for delivery in a sale of goods is the seller's place of business is a default rule because parties can make an enforceable contract requiring delivery at some other location. In contrast, the legal rule giving a consumer the right that goods purchased not be "in a defective condition unreasonably dangerous to the user" is mandatory because it applies no matter what the contract terms say. The distinction between mandatory and default rules is fundamentally important because it reveals the extent of contractual freedom. Mandatory rules limit the freedom of contract, while default rules permit it. (Arbitration Law in America: A Critical Assessment edited by Edward Brunet)

Freedom of contract is the freedom of individuals and groups (such as corporations) to form contracts without government restrictions. This is opposed to government restrictions such as minimum wage, competition law, or price fixing. Through freedom of contract, individuals entail a general freedom to choose with whom to contract, whether to contract or not, and on which terms to contract. (Wikipedia)

Freedom of Contract The ability of parties to bargain and create the terms of their agreement as they desire without outside interference from government. (wex (legal dictionary and encyclopedia sponsored and hosted by the Legal Information Institute at the Cornell Law School))