Suspect Classification a presumptively unconstitutional distinction made between individuals on the basis of race, national origin, alienage, or religious affiliation, in a statute, ordinance, regulation, or policy. The U.S. Supreme Court has held that certain kinds of government discrimination are inherently suspect and must be subjected to strict judicial scrutiny. The suspect classification doctrine has its constitutional basis in the Fifth Amendment and the equal protection clause of the Fourteenth Amendment, and it applies to actions taken by federal and state governments.
Racial classifications are automatically suspect, so courts apply the highest level of scrutiny and almost always strike down racial classifications. There is no definitive list of suspect classifications, but the Supreme Court typically treats as suspect any classification of people who, have an inherent trait, have a trait that is highly visible, as a class, have been disadvantaged historically, or are part of a group that has historically lacked effective representation in the political process. Racial and ethnic classifications are to satisfy the strict scrutiny, suspect classifications such as race, alienage, or national origin must be necessary to promote a compelling state interest when there is no less restrictive alternative method available to accomplish the government interest.
The practical result of this legal doctrine is that government sponsored discrimination on the account of a citizen's race, skin color, ethnicity, religion, or national origin is almost always unconstitutional, unless it is a compelling, narrowly tailored and temporary piece of legislation dealing with national security, defense, or affirmative action suspect classifications most often given strict scrutiny.
Reference
Collapsing Suspect Class with Suspect Classification Sonu Bedi Assistant Professor Department of Government Dartmouth College