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8.2 Sources of Contract Law

Learning Objectives

  1. Understand that contract law comes from two sources: judges (cases) and legislation.
  2. Know what the Restatement of Contracts is.
  3. Recognize the Convention on Contracts for the International Sale of Goods.

The most important sources of contract law are state case law and state statutes (though there are also many federal statutes governing how contracts are made by and with the federal government).

Case Law

Law made by judges is called case lawLaw decided by judges as recorded in cases and published.. Because contract law was made up in the common-law courtroom by individual judges as they applied rules to resolve disputes before them, it grew over time to formidable proportions. By the early twentieth century, tens of thousands of contract disputes had been submitted to the courts for resolution, and the published opinions, if collected in one place, would have filled dozens of bookshelves. Clearly this mass of material was too unwieldy for efficient use. A similar problem also had developed in the other leading branches of the common law.

Disturbed by the profusion of cases and the resulting uncertainty of the law, a group of prominent American judges, lawyers, and law teachers founded the American Law Institute (ALI) in 1923 to attempt to clarify, simplify, and improve the law. One of the ALI’s first projects, and ultimately one of its most successful, was the drafting of the Restatement of the Law of ContractsAn organized codification of the common law of contracts., completed in 1932. A revision—the Restatement (Second) of Contracts—was undertaken in 1964 and completed in 1979. Hereafter, references to “the Restatement” pertain to the Restatement (Second) of Contracts.

The Restatements—others exist in the fields of torts, agency, conflicts of laws, judgments, property, restitution, security, and trusts—are detailed analyses of the decided cases in each field. These analyses are made with an eye to discerning the various principles that have emerged from the courts, and to the maximum extent possible, the Restatements declare the law as the courts have determined it to be. The Restatements, guided by a reporter (the director of the project) and a staff of legal scholars, go through several so-called tentative drafts—sometimes as many as fifteen or twenty—and are screened by various committees within the ALI before they are eventually published as final documents.

The Restatement (Second) of Contracts won prompt respect in the courts and has been cited in innumerable cases. The Restatements are not authoritative, in the sense that they are not actual judicial precedents; but they are nevertheless weighty interpretive texts, and judges frequently look to them for guidance. They are as close to “black letter” rules of law as exist anywhere in the American common-law legal system.

Common law, case law (the terms are synonymous), governs contracts for the sale of real estate and services. “Services” refer to acts or deeds (like plumbing, drafting documents, driving a car) as opposed to the sale of property.

Statutory Law: The Uniform Commercial Code

Common-law contract principles govern contracts for real estate and services. Because of the historical development of the English legal system, contracts for the sale of goods came to be governed by a different body of legal rules. In its modern American manifestation, that body of rules is an important statute: the Uniform Commercial Code (UCC)The modern American state statutory law governing commercial transactions., especially Article 2That part of the Uniform Commercial Code dealing with the sale of goods., which deals with the sale of goods.

History of the UCC

A bit of history is in order. Before the UCC was written, commercial law varied, sometimes greatly, from state to state. This first proved a nuisance and then a serious impediment to business as the American economy became nationwide during the twentieth century. Although there had been some uniform laws concerned with commercial deals—including the Uniform Sales Act, first published in 1906—few were widely adopted and none nationally. As a result, the law governing sales of goods, negotiable instruments, warehouse receipts, securities, and other matters crucial to doing business in an industrial market economy was a crazy quilt of untidy provisions that did not mesh well from state to state.

The UCC is a model law developed by the ALI and the National Conference of Commissioners on Uniform State Laws; it has been adopted in one form or another by the legislatures in all fifty states, the District of Columbia, and the American territories. It is a “national” law not enacted by Congress—it is not federal law but uniform state law.

Initial drafting of the UCC began in 1942 and was ten years in the making, involving the efforts of hundreds of practicing lawyers, law teachers, and judges. A final draft, promulgated by the ALI, was endorsed by the American Bar Association and published in 1951. Various revisions followed in different states, threatening the uniformity of the UCC. The ALI responded by creating a permanent editorial board to oversee future revisions. In one or another of its various revisions, the UCC has been adopted in whole or in part in all American jurisdictions. The UCC is now a basic law of relevance to every business and business lawyer in the United States, even though it is not entirely uniform because different states have adopted it at various stages of its evolution—an evolution that continues still.

Organization of the UCC

The UCC consists of nine major substantive articles; each deals with separate though related subjects. The articles are as follows:

  • Article 1: General Provisions
  • Article 2: Sales
  • Article 2A: Leases
  • Article 3: Commercial Paper
  • Article 4: Bank Deposits and Collections
  • Article 4A: Funds Transfers
  • Article 5: Letters of Credit
  • Article 6: Bulk Transfers
  • Article 7: Warehouse Receipts, Bills of Lading, and Other Documents of Title
  • Article 8: Investment Securities
  • Article 9: Secured Transactions

Article 2 deals only with the sale of goods, which the UCC defines as “all things…which are movable at the time of identification to the contract for sale other than the money in which the price is to be paid.”Uniform Commercial Code, Section 2-105. The only contracts and agreements covered by Article 2 are those relating to the present or future sale of goods.

Article 2 is divided in turn into six major parts: (1) Form, Formation, and Readjustment of Contract; (2) General Obligation and Construction of Contract; (3) Title, Creditors, and Good Faith Purchasers; (4) Performance; (5) Breach, Repudiation, and Excuse; and (6) Remedies. These topics will be discussed in Chapter 17 "Introduction to Sales and Leases", Chapter 18 "Title and Risk of Loss", Chapter 19 "Performance and Remedies", Chapter 20 "Products Liability", and Chapter 21 "Bailments and the Storage, Shipment, and Leasing of Goods".

Figure 8.1 Sources of Law

International Sales Law

The Convention on Contracts for the International Sale of Goods

A Convention on Contracts for the International Sale of Goods (CISG)An international body of contract law. was approved in 1980 at a diplomatic conference in Vienna. (A convention is a preliminary agreement that serves as the basis for a formal treaty.) The CISG has been adopted by more than forty countries, including the United States.

The CISG is significant for three reasons. First, it is a uniform law governing the sale of goods—in effect, an international Uniform Commercial Code. The major goal of the drafters was to produce a uniform law acceptable to countries with different legal, social, and economic systems. Second, although provisions in the CISG are generally consistent with the UCC, there are significant differences. For instance, under the CISG, consideration (discussed in Chapter 11 "Consideration") is not required to form a contract, and there is no Statute of Frauds (a requirement that certain contracts be evidenced by a writing). Third, the CISG represents the first attempt by the US Senate to reform the private law of business through its treaty powers, for the CISG preempts the UCC. The CISG is not mandatory: parties to an international contract for the sale of goods may choose to have their agreement governed by different law, perhaps the UCC, or perhaps, say, Japanese contract law. The CISG does not apply to contracts for the sale of (1) ships or aircraft, (2) electricity, or (3) goods bought for personal, family, or household use, nor does it apply (4) where the party furnishing the goods does so only incidentally to the labor or services part of the contract.

Key Takeaway

Judges have made contract law over several centuries by deciding cases that create, extend, or change the developing rules affecting contract formation, performance, and enforcement. The rules from the cases have been abstracted and organized in the Restatements of Contracts. To facilitate interstate commerce, contract law for many commercial transactions—especially the sale of goods—not traditionally within the purview of judges has been developed by legal scholars and presented for the states to adopt as the Uniform Commercial Code. There is an analogous Convention on Contracts for the International Sale of Goods, to which the United States is a party.


  1. How do judges make contract law?
  2. What is the Restatement of the Law of Contracts, and why was it necessary?
  3. Why was the Uniform Commercial Code developed, and by whom?
  4. Who adopts the UCC as governing law?
  5. What is the Convention on Contracts for the International Sale of Goods?