Strict scrutiny is the most demanding standard of review for judging the constitutionality of a law. It requires the government to prove that the law is necessary to further a compelling government interest. The law must be narrowly tailored and use the least restrictive means to further this interest. Laws generally do not pass this standard of review. It is often applied in equal protection cases involving classifications based on certain protected traits, such as race, national origin, alienage (lack of citizenship), and religion. A lesser standard of review applies to certain other classifications, such as gender.