What is the test for equal protection under the Fifth Amendment?

Equal protection under the Fifth Amendment guarantees no substantive rights or liberties. Harris v. McRae, 448 U.S. 297, 322, 100 S.Ct. 2671, 65 L.Ed.2d 784 (1980). Rather, it entrenches a right to be free from discrimination based on impermissible statutory classifications and other governmental action. Id. Where such classification is not predicated on membership in a suspect or quasi-suspect class, the Constitution requires only that the classification rest on grounds reasonably related to the achievement of any legitimate governmental objective. Id. (explaining rational basis scrutiny).