So for discriminatory laws to be overturned the Supreme Court looks at them with three levels of scrutiny. If a law discriminates on the basis of race, ethnicity, or alienage then it faces strict scrutiny and these laws are almost never upheld, it has to be for a compelling government interest and be the least discriminatory means of achieving it. There’s another level which is for discrimination on the basis of gender or legitimacy (whether you were born out of wedlock) and this is for intermediate review, about half of these laws are upheld. Next you have rational review which is for everything else (disability, age, class etc.) and these laws are almost always upheld- basically if you can come up with any rational justification for it the law won’t be struck down. Basically this means that if a law discriminates based on race it’s going to be a lot easier to get it struck down than if it discriminates based on class which legacy does. I’m not defending the system just explaining.