Rational Basis Law and Legal Definition

Rational basis a test used to determine the constitutionality of a statute, asking whether the law has a reasonable connection to achieving a legitimate and constitutional objective. Under this traditional test, a state law must be upheld if it (or the classification it contains) is rationally related to any legitimate interest of the state. Moreover, the legitimate interest of the state need not be one that actually motivated legislators to enact the legislation. It is enough if the interest is now advanced and that it is "conceivable."

However, for laws involving a fundamental right, courts increas its scrutiny of the government's action, requiring that the means be necessary to achieve a compelling state interest.