American constitutional law developed the suspect classification doctrine to place specific types of government discrimination, which effectively infringe on the civil rights of a suspect class, under heightened scrutiny.
Suspect classifications fall under the Fifth and Fourteenth Amendments, and place the burden of proving that the discrimination is constitutional on the government.
The term "suspect classification" is taken from Supreme Court Justice Hugo Black’s majority opinion in Korematsu v. United States. The constitutionality of the Japanese internment camps during World War II was at issue. Justice Black wrote that government policies affecting the civil rights of “a single group are immediately suspect.” Justice Black’s words formed the basis of civil rights victories under the Equal Protection Clause.
There are several classifications considered suspect, including race, religion and ethnicity.