Law of the United States
The law of the United States comprises many levels[1] of codified and uncodified forms of law, of which the most important is the nation's Constitution, which prescribes the foundation of the federal government of the United States, as well as various civil liberties. The Constitution sets out the boundaries of federal law, which consists of Acts of Congress,[2] treaties ratified by the Senate,[3] regulations promulgated by the executive branch,[4] and case law originating from the federal judiciary.[5] The United States Code is the official compilation and codification of general and permanent federal statutory law.
Federal law and treaties, so long as they are in accordance with the Constitution, preempt conflicting state and territorial laws in the 50 U.S. states and in the territories.[6] However, the scope of federal preemption is limited because the scope of federal power is not universal. In the dual sovereign[7] system of American federalism (actually tripartite[8] because of the presence of Indian reservations), states are the plenary sovereigns, each with their own constitution, while the federal sovereign possesses only the limited supreme authority enumerated in the Constitution.[9] Indeed, states may grant their citizens broader rights than the federal Constitution as long as they do not infringe on any federal constitutional rights.[10][11] Thus U.S. law (especially the actual "living law" of contract, tort, property, criminal, and family law experienced by the majority of citizens on a day-to-day basis) consists primarily of state law, which can and does vary greatly from one state to the next.[12][13]
At both the federal and state levels, with the exception of the legal system of Louisiana, the law of the United States is largely derived from the common law system of English law, which was in force in British America at the time of the American Revolutionary War.[14][15] However, American law has diverged greatly from its English ancestor both in terms of substance and procedure[16] and has incorporated a number of civil law innovations.
Levels of law[edit]
Federal law[edit]
Federal law originates with the Constitution, which gives Congress the power to enact statutes for certain limited purposes like regulating interstate commerce. The United States Code is the official compilation and codification of the general and permanent federal statutes. Many statutes give executive branch agencies the power to create regulations, which are published in the Federal Register and codified into the Code of Federal Regulations. Regulations generally also carry the force of law under the Chevron doctrine. Many lawsuits turn on the meaning of a federal statute or regulation, and judicial interpretations of such meaning carry legal force under the principle of stare decisis.
During the 18th and 19th centuries, federal law traditionally focused on areas where there was an express grant of power to the federal government in the federal Constitution, like the military, money, foreign relations (especially international treaties), tariffs, intellectual property (specifically patents and copyrights), and mail. Since the start of the 20th century, broad interpretations of the Commerce and Spending Clauses of the Constitution have enabled federal law to expand into areas like aviation, telecommunications, railroads, pharmaceuticals, antitrust, and trademarks. In some areas, like aviation and railroads, the federal government has developed a comprehensive scheme that preempts virtually all state law, while in others, like family law, a relatively small number of federal statutes (generally covering interstate and international situations) interacts with a much larger body of state law. In areas like antitrust, trademark, and employment law, there are powerful laws at both the federal and state levels that coexist with each other. In a handful of areas like insurance, Congress has enacted laws expressly refusing to regulate them as long as the states have laws regulating them (see, e.g., the McCarran–Ferguson Act).