The compelling state interest test refers to one of several methods of determining whether a law is constitutional.
Although not explicitly defined, “compelling” is clearly intended to be a higher interest than “legitimate” or “important,” and some have described it as “necessary” or “crucial”—meaning more than an exercise of discretion or preference.
The compelling state interest test is a major component of the strict scrutiny doctrine, a doctrine applied in judicial review of government statutes and actions which burden or restrict certain fundamental constitutional rights.
Strict scrutiny is applied only in certain contexts, such as cases where the government action in question limits speech based upon the content of the speech; or cases involving discrimination based on race, religion, national origin or other similar classifications; or cases in which the strict scrutiny doctrine must be applied as required by the Religious Freedom Restoration Act or the Religious Land Use and Institutionalized Persons Act.
Where strict scrutiny applies, the government action is found to be unconstitutional unless it is deemed the action was necessary to further a compelling government interest, and that it furthers such an interest by the least restrictive means. This is what is called the compelling state interest test.
If strict scrutiny does not apply, the compelling state interest test also does not apply. Instead, a court may review the government action under what is called “intermediate scrutiny” where the government interest need only be “substantial” rather than compelling (substantial still being a meaningful restriction on government action), or under “rational basis scrutiny,” which merely requires that the action be reasonable and rational under the circumstances. Under rational basis inquiry, few government actions are disallowed by the courts.