In U.S. constitutional law, when a law infringes upon a fundamental constitutional right, the court may apply the strict scrutiny standard. Strict scrutiny holds the challenged law as presumptively invalid unless the government can demonstrate that the law or regulation is necessary to achieve a "compelling state interest". The government must also demonstrate that the law is "narrowly tailored" to achieve that compelling purpose, and that it uses the "least restrictive means" to achieve that purpose. Failure to meet this standard will result in striking the law as unconstitutional. The standard is the highest and most stringent standard of judicial review and is part of the levels of judicial scrutiny that courts use to determine whether a constitutional right or principle should give way to the government's interest against observance of the principle. The lesser standards are rational basis review and exacting or intermediate scrutiny. These standards are applied to 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. (1938), one of a series of decisions testing the constitutionality of New Deal legislation. One of the most notable cases in which the Supreme Court applied the strict scrutiny standard and found the government's actions constitutional was Korematsu v. United States (1944), in which the Court upheld the forced relocation of Japanese Americans in internment camps during World War II. In another case, it has been held that restricting access to unapproved prescription drugs is a compelling government interest. The burden of proof falls on the state in cases that require strict scrutiny or intermediate scrutiny, but not the rational basis. 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 satisfy the strict scrutiny standard, the law or policy 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