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 United States Constitution, the foundation of the federal government of the United States. 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 laworiginating 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, most 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, the law of the United States is largely derived from the common law system of English law, which was in force at the time of the 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.

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General overview[edit]

Law affects every aspect of American life, includingparking lots. Note the citations to statutes on the sign.

Sources of law[edit]

In the United States, the law is derived from five sources: constitutional law, statutory law, treaties, administrative regulations, and the common law (which includes case law).^[17]

Constitutionality[edit]

Where Congress enacts a statute that conflicts with the Constitution, the Supreme Court may find that law unconstitutional and declare it invalid.^[18]

Notably, a statute does not disappear automatically merely because it has been found unconstitutional; it must be deleted by a subsequent statute. Many federal and state statutes have remained on the books for decades after they were ruled to be unconstitutional. However, under the principle of stare decisis, no sensible lower court will enforce an unconstitutional statute, and any court that does so will be reversed by the Supreme Court.^[19] Conversely, any court that refuses to enforce a constitutional statute (where such constitutionality has been expressly established in prior cases) will risk reversal by the Supreme Court.^[20][21]

American common law[edit]

The United States and most Commonwealth countries are heirs to the common law legal tradition of English law.^[22] Certain practices traditionally allowed under English common law were expressly outlawed by the Constitution, such as bills of attainder^[23] and general search warrants.^[24]

As common law courts, U.S. courts have inherited the principle of stare decisis.^[25] American judges, like common law judges elsewhere, not only apply the law, they also make the law, to the extent that their decisions in the cases before them become precedent for decisions in future cases.