In American constitutional law, strict scrutiny is the highest and most stringent standard of judicial review, and results in a judge striking down a law unless the government can demonstrate in court that a law or regulation:
is necessary to a "compelling state interest";
is "narrowly tailored" to achieving this compelling purpose; and
uses the "least restrictive means" to achieve the purpose.
It is part of the hierarchy of standards that courts use to determine which is weightier: a constitutional right or principle, or the government's interest against observance of the principle. The lesser standards are rational basis review and exacting or intermediate scrutiny. These standards are used to test statutes and government action at all levels of government within the United States. The notion of "levels of judicial scrutiny", including strict scrutiny, was introduced in Footnote 4 of the U.S. Supreme Court decision in United States v. Carolene Products Co., one of a series of decisions testing the constitutionality of New Deal legislation. The first and most notable case in which the Supreme Court applied the strict scrutiny standard and found the government's actions constitutional was Korematsu v. United States, in which the Court upheld the forced relocation of Japanese Americans in internment camps during World War II.
Applicability
U.S. courts apply the strict scrutiny standard in two contexts: when a fundamental constitutional right is infringed, particularly those found in the Bill of Rights and those the court has deemed a fundamental right protected by the Due Process Clause or "liberty clause" of the 14th Amendment, or when a government action applies to a "suspect classification", such as race or national origin. To pass strict scrutiny, the law or policy must satisfy three tests:
It must be justified by a compelling governmental interest. While the Courts have never brightly defined how to determine if an interest is compelling, the concept generally refers to something necessary or crucial, as opposed to something merely preferred. Examples include national security, preserving the lives of a large number of individuals, and not violating explicit constitutional protections.
The law or policy must be narrowly tailored to achieve that goal or interest. If the government action encompasses too much or fails to address essential aspects of the compelling interest, then the rule is not considered narrowly tailored.
The law or policy must be the least restrictive means for achieving that interest: there must not be a less restrictive way to effectively achieve the compelling government interest. The test will be met even if there is another method that is equally the least restrictive. Some legal scholars consider this "least restrictive means" requirement part of being narrowly tailored, but the Court generally evaluates it separately.
Legal scholars, including judges and professors, often say that strict scrutiny is "strict in theory, fatal in fact" since popular perception is that most laws subjected to the standard are struck down. However, an empirical study of strict scrutiny decisions in the federal courts found that laws survive strict scrutiny more than 30% of the time. In one area of law, religious liberty, laws that burden religious liberty survived strict scrutiny review in nearly 60% of cases. However, a discrepancy was found in the type of religious liberty claim, with most claims for exemption from law failing and no allegedly discriminatory laws surviving. See also the cases cited below, however; several appear to permit the exemption from laws based upon religious liberty. Harvard law professor Richard Fallon, Jr. has written that, rather than being neatly applied, strict scrutiny’s “interpretation is more varied than is often recognized”, a view that has been acknowledged by at least one U.S. Supreme Court Justice, Clarence Thomas. The compelling state interest test is distinguishable from the rational basis test, which involves claims that do not involve a suspect class and involve a liberty interest rather than a fundamental right. It is also important to note that, unlike the rational basis test, the burden of proof falls on the state in cases that require strict scrutiny or intermediate scrutiny.
Suspect classification
The Supreme Court has established standards for determining whether a statute or policy's classification requires the use of strict scrutiny. The class must have experienced a history of discrimination, must be definable as a group based on "obvious, immutable, or distinguishing characteristics," be a minority or "politically powerless," and its characteristics must have little relationship to the government's policy aims or the ability of the group's members to contribute to society. The Court has consistently found that classifications based on race, national origin, and alienage require strict scrutiny review. The Supreme Court held that all race-based classifications must be subjected to strict scrutiny in Adarand Constructors v. Peña, 515 U.S. 200, overruling Metro Broadcasting, Inc. v. FCC, 497 U.S. 547, which had briefly allowed the use of intermediate scrutiny to analyze the Equal Protection implications of race-based classifications in the narrow category of affirmative-action programs established by the federal government in the broadcasting field.
''De jure'' versus ''de facto'' discrimination
As applied in Korematsu v. United States, which upheld the race-based exclusion order and internment during World War II of Japanese Americans who had resided on the West Coast of the United States, strict scrutiny was limited to instances of de jure discrimination, where a racial classification is written into the language of a statute. The Supreme Court's decision in Village of Arlington Heights v. Metropolitan Housing Development Corp. provided further definition to the concept of intent and clarified three particular areas in which intent of a particular administrative or legislative decision becomes apparent, the presence of any of which demands the harsher equal protection test. The Court must use strict scrutiny if one of these tests, among others, is met:
the impact is so "stark and dramatic" as to be unexplainable on non-racial grounds, as in Yick Wo v. Hopkins
the historical background of the decision suggests intent
the legislative and administrative records leading up to the decision show intent
One, Inc. v. Olesen, 301 U.S. 340, ending censorship of homosexual publications
Sherbert v. Verner, 374 U.S. 398, invalidating state law denying unemployment benefits to employees fired for refusing to violate their religious belief.
Griswold v. Connecticut, 381 U.S. 479, striking down prohibition of contraceptives birth control
Loving v. Virginia, 897 U.S. 113, striking down prohibition of interracial marriage miscegenation
Wisconsin v. Yoder, 406 U.S. 205, striking down law requiring all minors to attend public school, thereby permitting Amish to remove their children from public schools after 8th grade
Roe v. Wade, 410 U.S. 113, striking down ban on abortion
Employment Division v. Smith, 494 U.S. 872, allowing states to deny unemployment benefits to those using illegal drugs for religious purposes
Romer v. Evans, 380 U.S. 144, invalidating Colorado state constitutional amendment prohibiting enactment of local anti-discrimination protections for homosexuals
City of Boerne v. Flores, 521 U.S. 507, holding that some zoning laws may be an undue restriction of religious freedom
Gonzales v. O Centro Espírita Beneficente União do Vegetal, 546 U.S. 418, allowing religious use of illegal drugs
United States v. Windsor, 570 U.S. 744, striking down the limitation of marriage licenses only to heterosexual couples