The Amendment, and the clause, were enacted shortly after the Civil War. Although the primary goal of the clause was to attain free and equal treatment for ex-slaves, it has been interpreted as imposing a general restraint on the government's power to classify people, not just classifications based on race but also those based on sex, alienage, illegitimacy, wealth, or any other characteristic.
By its terms, the clause restrains only state governments. Nonetheless the federal government is bound by the same rules of equal protection under the 5th Amendment.
Analysis of Equal Protection violations begins with the classification the government has made. In other words, how is the government distinguishing among people? Is the law or government action race, sex, or status as an alien? Where the classification exists on the face of the law, is where the law draws a distinction among people based on a particular characteristic. If someone attacks a classification that is clearly written into a statute or regulation, then they are claiming that their Equal Protection is violated by that statute or regulation “on its face.” If someone says that a statute is being administered in a purposefully discriminatory way, then they are claiming that the statute is facially neutral. In order to demonstrate that a facially neutral law has a discriminatory impact it must also have a discriminatory purpose.
Next, you must locate what the appropriate standard or level of scrutiny is to use. Differing levels of scrutiny will be applied depending on the type of scrutiny and the history of discrimination against that particular group.
Discrimination based on race or national origin (aliens) is subjected to strict scrutiny. Strict scrutiny is a law that is upheld if it is proven necessary to achieve a compelling government purpose. The Court will give strict scrutiny to any statute which impairs a fundamental right. Must be the least restrictive means available (or necessary) to achieve a compelling state interest. The government must have a truly significant reason for discriminating, and it must show that it cannot achieve its objective through any less discriminatory alternative and the government has the burden of proof.
Then there is intermediate scrutiny which is used for discrimination based on gender and non-marital children. A law is upheld if it is substantially related to an important government purpose --“substantial relationship” and the government has the burden of proof. The notion is that it is unfair to penalize a person for characteristics that the person did not chose and that the individual cannot change.
The final standard is the rational basis standard. This is where a law will be upheld if it is rationally related to a legitimate government purpose. The challenged law must be a reasonable measure designed to achieve a legitimate governmental purpose. The challenger has the burden of proof and all laws not subjected to strict scrutiny or intermediate scrutiny are evaluated under the rational basis test.
You must also find the purpose. Classifications are okay for some purposes and not the other; all tests require some correlation between the classification and the law. You should look at the history of the statute or law and it is extremely relevant who actually proposed it, incentives based on good performance, if there is some racially motivated purpose you can shift the burden, otherwise it is the plaintiff’s burden. Everything is relevant when using circumstantial evidence to prove intent. Then analyze how necessary the classification is to achieving purpose and in applying the standard. Look at how relatively close the purpose and the classification are?
By doing this analysis you can determine whether the statute, regulation or law is violating a persons equal protection rights instilled by the United States Constitution. This clause guarantees that people or groups who are similarly situated will be treated similarly and vice versa, people that are not similarly situated will not be treated similarly.