When a statute is challenged under equal protection, what is the legal test applied to determine its constitutionality?

Similarly, when a statute's constitutionality is challenged under equal protection, a court must analyze whether the classifications drawn by [the] statute constitute an arbitrary and invidious discrimination. Loving v. Virginia, 388 U.S. 1, 9, 87 S.Ct. 1817, 18 L.Ed.2d 1010 (1967). The level of scrutiny applied in analyzing the constitutionality of the statute, whether it is rational basis or a more heightened scrutiny, depends on the classification created by the legislation. See Id. at 11, 87 S.Ct. 1817. Which level of scrutiny a court uses in determining a statute's constitutionality has a major impact on whether the law is upheld as constitutional.