Equal Protection Clause
The Equal Protection Clause, found in section 1 of the Fourteenth Amendment, forbids any state to "deny to any person within its jurisdiction the equal protection of the laws." A state violates the Equal Protection Clause when it treats one person differently from another who is similarly situated without a rational basis for the disparate treatment. If there are racial or gender differences between the two examples, then the government must demonstrate more than a rational basis for the disparate treatment.
Recently, the Equal Protection Clause has been interpreted in a broader manner than before. For example, in Kansas, multiple lawsuits have been resolved in favor of claimants who have argued that the public school funding system discriminates against students in counties with smaller tax bases, and judges have ordered wealthier school districts to share money with other districts.
Use in abortion cases
The Equal Protection Clause is invoked by abortion clinics to try to invalidate laws that treat them differently than legitimate medical services.
But the U.S. Supreme Court has affirmed the authority of a state to prefer childbirth over abortion. Moreover, the Equal Protection Clause imposes an undemanding test with respect to facial challenges to economic legislation. "[I]f a law neither burdens a fundamental right nor targets a suspect class, we will uphold the legislative classification so long as it bears a rational relation to some legitimate end." Romer v. Evans, 517 U.S. 620, 631 (1996). "By requiring that the classification bear a rational relationship to an independent and legitimate legislative end, we ensure that classifications are not drawn for the purpose of disadvantaging the group burdened by the law." Id. at 633.
Only if a statute is issue "raise[s] the inevitable inference that the disadvantage imposed is born of animosity toward the class of persons affected," would an abortion statute be unconstitutional. In that case the "'desire to harm a politically unpopular group cannot constitute a legitimate governmental interest.'" Id. at 634-35 (quoting Department of Agriculture v. Moreno, 413 U.S. 528, 534 (1973)).