The substantial governmental interest test is a part of the intermediate or heightened scrutiny analysis in constitutional law, whereby the government interest need only be “substantial” rather than compelling in a case where it indirectly infringes on religious freedom.
It is applied not only in cases involving First Amendment claims, but also various claims of violations of due process and equal protection. It represents a governmental interest more than a legitimate interest but less than a compelling interest.
In modern constitutional law, there are three standards of review: (1) strict scrutiny; (2) intermediate or heightened scrutiny; and (3) rational basis. Strict scrutiny is the highest level of judicial review. Under it, the government must advance a compelling, or extremely important interest, advanced in the least restrictive way possible.