Law may be classified in several ways: by system (common and civil law), by source (constitutional, statutory, and case law), by the parties involved (public and private law), by substance (civil and criminal law), and by function (substantive and procedural law). Each of these classifications is discussed in the sections that follow.

Common Law and Civil Law Systems

The two primary systems of American law are the common law system and the civil law system. The common-law system, which developed in England, is the most prevalent system of law in North America. The civil law system in North America is strongest in Louisiana in the United States and in Quebec in Canada; it is also prevalent in Mexico.

The common-law system is based on precedent and the principle of stare decisis. Although the legislative bodies at the federal, state, and local levels enact written statutes, and sometimes collect portions of those statutes into “codes,” there is no formal, comprehensive code of common law. Instead, the common law is stated in court decisions, and it is changed or modified by subsequent cases or statutes.

The civil law system may be traced back to the Roman law from which most European law systems originated. It was brought to the Western Hemisphere by the French, Spanish, and Portuguese. The civil law system as it exists in Europe is the result of Napoleon Bonaparte’s efforts: he provided for the drafting of the Code Civil or Code Napoleon, which restated the earlier principles of Roman law in more modern terms. In the civil law system, the Code Civil is a general statement of legal principles that is looked to in the interpretation of statutes and cases, and civilian courts do not follow the principle of stare decisis. The civil law system also does not have a division between law and equity.

Constitutional Law

A constitution is the basic framework for a legal and governmental system. It defines basic principles of law that all other laws must follow and delegates authority to various officials and agencies. Constitutions are created by the people acting in their collective capacity as sovereign in the nation or state in which they live.

The United States Constitution is the supreme law of the United States. No other federal or state law, statute, or case may impose upon its provisions.

The U.S. Constitution is divided into three parts. The first part, Articles I s.VII, divides governmental power among the three branches of government (legislative, executive, and judicial) and between the federal and state governments, describes the relationships between the states, and sets out the means for amending the Constitution. Two methods are provided for proposing amendments (two thirds of both houses of Congress, or a Constitutional Convention called for by the legislatures of two thirds of the states), and two methods are provided for ratifying the proposed amendments (three fourths of the legislatures or three fourths of the conventions called in each state). By requiring a supermajority (i.e., at least two thirds), the framers made sure that any constitutional changes would have such general acceptance throughout the nation that the possibility of a legal challenge or outright rebellion would be minimized.

The second part of the Constitution is the Bill of Rights, which consists of the Constitution’s first ten amendments. The Tenth Amendment specifies that powers not reserved by the U.S. Constitution for the federal government reside with the states. The first nine amendments provide for and protect individual freedoms. The First Amendment provides for freedom of religion, speech, press, assembly, and petition for redress of grievances. Other amendments protect the ability to keep arms, the freedom from unreasonable searches and seizures, and the right to speedy and public jury trials in criminal cases and jury trials in civil cases. These have been among the most widely debated concepts in constitutional law.

The third part of the Constitution — the additional amendments that have been added over the past 200 years — reflects the efforts to keep it current with respect to changing social and political needs. These amendments cover a wide range of subjects. The Thirteenth Amendment abolished slavery in 1865. The Fourteenth Amendment granted the equal protection of the laws and due process of law to all the citizens and residents of the various states. The Fifteenth, Nineteenth, Twenty-fourth, and Twenty-sixth Amendments extended the right to vote. The Eighteenth Amendment prohibited the manufacture and sale of intoxicating beverages, and the Twenty-first Amendment repealed the Eighteenth Amendment.

States also have constitutions, which are often more detailed than the U.S. Constitution. When a court is interpreting a state constitution, it may find correctly that the state constitution gives people within that state more rights than the same language contained in the U.S. Constitution. Because of the supremacy clause of the U.S. Constitution, however, no state can give its people fewer rights than those in the U.S. Constitution.

Statutory Law

Statutes are enacted by the legislative branch of government (whether federal or state) to regulate areas within the legislature’s jurisdiction, as granted by the Constitution.

The United States Congress (by authority of Article I, Section 8, of the Constitution) has reserved to itself the power to regulate certain activities and functions, including patents, trademarks, copyrights, federal taxation, customs matters, the postal system, admiralty matters, bankruptcy, and diplomatic matters. It has the exclusive right to pass laws affecting these subjects. Congress also has power to pass legislation in areas not specifically assigned to it by the Constitution — such as labor and pollution control — that fall within its enumerated powers.

A law passed by Congress is not effective until it is signed into law by the president or has been repassed over the president’s veto by a two-thirds majority of each house of the Congress, or if the president takes no action within 10 days of receiving it. Laws are published at the end of each session of Congress in the Statutes at Large (Stat.), where the laws are arranged chronologically, and are ultimately compiled in the United States Code (U.S.C.), where the laws are grouped by subject. (Various private publishers also publish annotated editions of the United States Code.) This Code is organized into 50 titles or general subject areas (see Table).

Titles of the United States Code

  1. General Provisions
  2. The Congress
  3. The President
  4. Flag and Seal, Seat of Government and the States
  5. Government Organization and Employees
  6. Surety Bonds [repealed, and most provisions covered under title 31]
  7. Agriculture
  8. Aliens and Nationality
  9. Arbitration
  10. Armed Forces
  11. Bankruptcy
  12. Banks and Banking
  13. Census
  14. Coast Guard
  15. Commerce and Trade
  16. Conservation
  17. Copyrights
  18. Crimes and Criminal Procedure
  19. Customs Duties
  20. Education
  21. Food and Drugs
  22. Foreign Relations and Intercourse
  23. Highways
  24. Hospitals and Asylums
  25. Indians
  26. Internal Revenue Code
  27. Intoxicating Liquors
  28. Judiciary and Judicial Procedure
  29. Labor
  30. Mineral Lands and Mining
  31. Money and Finance
  32. National Guard
  33. Navigation and Navigable Waters
  34. Navy [eliminated by the enactment of title 10]
  35. Patents
  36. Patriotic Societies and Observances
  37. Pay and Allowances of the Uniformed Services
  38. Veterans’ Benefits
  39. Postal Service
  40. Public Buildings, Property, and Works
  41. Public Contracts
  42. The Public Health and Welfare
  43. Public Lands
  44. Public Printing and Documents
  45. Railroads
  46. Shipping
  47. Telegraphs, Telephones, and Radiotelegraphs
  48. Territories and Insular Possessions
  49. Transportation
  50. War and National Defense (with Appendix)

Each year the state legislatures also pass many laws, which become effective when they either receive gubernatorial approval or are passed over the governor’s veto. The exact titles of the state session laws — that is, the collections of statutes passed in each session of the state legislature — vary, as do the titles given to the state law compilations. In Michigan, for example, they are known as Michigan Compiled Laws; in Minnesota they are calledMinnesota Statutes Annotated; in North Dakota they are called the North Dakota Century Code. (Like the United States Code, some of these compilations are published in annotated editions by private law-book publishers.)

Relationship of constitutions, statutes, and the courts

Because of the supremacy clause in the Constitution, federal laws must comply only with the federal Constitution, but the laws of any state must comply with provisions of both the state constitution and the federal Constitution. In a conflict between a federal and a state law, the federal law preempts the state law.

Statutory law is superior to case law as a source of law, and courts ordinarily are bound to apply the relevant statutory law to the cases that they decide. However, if a state legislature were to pass a law in violation of the state constitution — for example, a law requiring that all textbooks be submitted to a review board — the appellate court in the state could declare the law unconstitutional. Courts will also interpret statutes and supply legal principles when no rule exists. Once the court issues a decision, the decision becomes part of the case law on the subject.

Case Law

Case law or common law is the law made by courts. It is known as case law because it derives from judicial decisions in legal cases rather than from written statutes. This means that as a court decides and reports its decision concerning a particular suit, this case becomes part of the body of law and can be consulted in later cases involving similar problems.

Prior to the development of constitutional and statutory law, controversies were decided on the basis of established customs. If there were no established customs, judges decided a case on the basis of what they considered to be right and wrong. As these decisions began to be recorded, judges were directed to look for guidance to the decision in a prior case that had similar facts. This use of precedents is known as stare decisis — literally, “to stand by (previous) decisions.” Stare decisis is important because it provides for consistency in the application of common law and offers some assurance to a person seeking relief in the courts as to the rules governing the likely outcome of the case.

Cases are published in reporters (such as United States Reports) that are produced either by the government or a private publishing firm. Not all cases are published.

Equity law

A review of the common law is not complete without examining equity law, which has its origins in English common law.

Since legal rules cannot be formulated to deal adequately with every possible contingency, applying them mechanically can sometimes result in injustice. To remedy such injustices, the law of equity was developed. The principle of equity is as old as the English common law, but it was hardly needed until the 14th century, since the law until that time was still relatively fluid and informal. As the common law became firmly established, however, its strict rules of proof began to cause hardship. Power to grant relief in situations involving potential injustices lay with the king and the lord chancellor. Eventually the chancellor’s jurisdiction developed into the Court of Chancery, whose function was to administer equity. The chancellor decided each case on its merits and had the right to grant or refuse relief without giving reasons, but common grounds for relief, such as fraud and breach of confidence, came to be recognized. And because the defendant could file an answer, a system of written pleadings developed.

Although a few states in the United States still have separate courts of equity and courts of law, most jurisdictions have merged the procedures of law and equity courts. Although the procedures are merged, the question of whether remedies are legal or equitable is important for determining whether a plaintiff is entitled to a jury trial. Equity law continues to provide unusual and personal remedies for legal disputes of a civil nature. Two of the most familiar equity decrees are the injunction and specific performance. An injunction restrains a party from doing something that would cause irreparable harm if not enjoined or temporarily halted. For example, an injunction may order a manufacturer to stop dumping certain chemicals into a river. Specific performance requires the performance of a duty agreed on in a contract or other agreement.

Public and Private Law

Another classification of laws is based on the scope of the laws, that is, on the parties to whom they apply. This classification includes public and private law.

Private law governs the relationship between private citizens. Disputes may involve property, contracts, negligence, wills, and any number of other matters. Occasionally, as in marriage and divorce, the state may be involved indirectly, but, as the state is not itself a litigant, the matter remains one of private law.

Public law is a branch of law concerned with regulating the relations of individuals among themselves and with the government as well as the organization and conduct of government itself. Public-law disputes involve the state or its agencies in a direct manner. Usually the state is a litigant; it is often the plaintiff, the party bringing the suit to court. Examples of public law are municipal law, township law, criminal law, admiralty law, securities law, social security law, and aviation law.

When individual laws are referred to, however, there is a different kind of distinction between public and private laws. Specifically, a private law is a law that affects only selected individuals or localities, while a public law affects the welfare of the whole governed unit. A private law provides a kind of exception to the public rule.

Administrative law has become a major part of public law. Administrative law comprises the rules and regulations framed and enforced by a federal or state administrative agency as well as any rulings that the agency makes. Administrative bodies, while primarily executive in nature, may be delegated some legislative or judicial authority. For example, the Federal Aviation Administration not only issues regulations for air transportation but also adjudicates some disputes between airlines and their customers. The rules and regulations created by the federal administrative agencies are first published chronologically in the Federal Register (Fed. Reg.) and then later organized by subject in the Code of Federal Regulations (C.F.R.). See Important Agencies for information on some of the federal agencies.

State and local governments also have administrative agencies that issue rules, regulations, and rulings. They may be a part of an executive department of the state government or they may be independent entities. These agencies tend to regulate areas not preempted by federal agencies, but they may also be found in fields subject to both federal and state regulation. State administrative agencies often have jurisdiction over these areas: unemployment and workers’ compensation, taxation, education, motor vehicles, zoning, and health and safety. States publish their administrative law in compilations similar to the Federal Register and Code of Federal Regulations.

Civil and Criminal Law

Cases that come before a court may generally be divided into two categories: civil and criminal. Civil law deals with acts that injure a person or a person’s rights. Civil law provides remedies, such as monetary damages or declaratory relief, that are intended primarily to compensate the injured party. Civil law covers numerous areas, including real estate, domestic relations, partnership, taxes, contracts, and wills and trusts.

Criminal law declares what conduct is criminal and prescribes the punishment to be imposed for it. A criminal action is always prosecuted in the name of the federal government (“The United States of America”), the state (“The People of the State”), or a political subdivision, because the case is based on the alleged violation of the rights of all the people. The remedy sought in a criminal case is intended to punish the offender. The major categories of crimes are crimes against the person (as homicide or assault) or crimes against property (as arson or theft). A single act may be the basis for both civil and criminal penalties.

Substantive and Procedural Law

Substantive law consists of the statutory and case law setting forth rights and obligations upon which a controversy is based, whereas procedural oradjective law states the rules by which a person can secure his or her substantive rights. Thus, procedural law consists of the rules of procedure or practice according to which the substantive law is administered. Procedural law deals with pleadings, which are papers that pass between the parties;practice, which refers to the conduct of litigation; and evidence, or the admissibility of evidence to achieve fairness while avoiding unnecessary expense or delay.

Although procedural law does not state the law, it outlines the procedures that must be followed in applying the substantive law. Procedural law enables the attorney to decide whether a case should go to federal or state court. It will tell the attorney when a lawsuit must be started, what pleadings are required of all parties, and what kind of evidence can be presented at trial. Procedural law can be as important as the substantive law in determining the outcome of a case because a case may be thrown out if the proper procedures are not followed.