Law is the framework within which people, organizations and governments are expected to behave. It provides both acceptable and unacceptable ways to act, and failure to follow a law can result in penalties. Examples of laws include traffic laws, seat belt laws and school bus laws.

Legal systems vary significantly across countries and continents, but the basic structures, concepts and rules of these systems have much in common. They are based on principles, standards and norms drawn from Roman law and sometimes supplemented by local custom and culture.

The main purposes of law are to establish standards, maintain order, resolve disputes and protect liberties and rights. Different systems are better at these functions than others.

There are four principal types of law: civil law, administrative law, criminal law and commercial law. Generally speaking, each of these includes the three core subjects: property, contracts and evidence.

Property law covers ownership of land, homes and other properties; commercial law involves trade and business; and administrative law governs the operation of governmental agencies.

Constitutional law refers to the laws that form the basis of the legal system and the judicial decisions that determine what is considered legal or unlawful behavior. The United States Constitution is the highest law of the country, and federal courts interpret and enforce this document as a basis for a legal system.

The practice of law is a complex process that encompasses many areas and requires knowledge of multiple topics. Lawyers are the experts in this field, and they may work in a variety of settings including government agencies, businesses and nonprofit organizations.

A lawyer may represent either the plaintiff or the defendant in a case. The lawyer’s job is to explain the case to the court and argue on behalf of either side.

There are also a number of other related fields that lawyers can specialize in. For example, labour law covers the tripartite industrial relationship between the worker, the employer and the trade union. This includes collective bargaining regulation and the right of strikers to strike.

Appeals are requests made after a trial that ask another court (usually the court of appeals) to review the judge’s decision and decide whether the case was properly handled. Often, an appeal is based on errors in procedure or the judge’s interpretation of the law.

Statutes are laws that are passed by Congress and signed by the President of the United States. These laws can establish new authorities, change existing authorities, or amend previously enacted authorities.

Drafting a statute is an art and takes years of experience, research, and skill. Legislative committees and commissions often study a topic for a year or more before writing a bill.

In bicameral legislatures, such as those in the United States, a bill must be passed through both houses in the same form to become a law. When the two houses cannot agree, a procedure of compromise is usually used to produce a final version for consideration by the executive branch.