Law is a body of rules enforced by a sovereign power. It governs relationships among people and between states. It shapes politics, economics and history in many ways and serves as a mediator of relations between people. Law is often influenced by morals and beliefs, but it differs from mere suggestion or good advice in that there are penalties, such as fines, imprisonment and other sanctions.
The legal system varies worldwide, and the law itself can be interpreted in different ways. In the United States, federal law consists of statutes (passed by Congress), treaties ratified by the Senate, regulations promulgated by executive branch agencies and case law decided by the federal judiciary. State laws regulating insurance, family law, criminal and civil procedure, contract, tort and property are enacted by state legislatures.
There are also laws relating to specific activities, such as aviation, carriage of goods, bankruptcy, copyright, trademark and labor law. In most areas, the law at the federal and state levels coexist, except where a limited number of federal statutes preempt all state laws, such as interstate commerce, military matters, money and foreign affairs (including international treaties), patents and copyrights, and mail. The law at the state and local levels can include constitutional provisions, statutes passed by the legislature, regulations created by the executive branch, and case law handed down by the courts. In common law systems, decisions by higher courts bind lower courts through the doctrine of stare decisis.