Final answer:
The equal protection clause allows for legal discrimination, such as age restrictions and academic requirements, when these distinctions serve a legitimate state interest and are rationally related to that interest, as determined by the rational basis test.
Step-by-step explanation:
The equal protection clause of the Fourteenth Amendment to the U.S. Constitution does require that individuals in similar situations be treated equally under the law. However, this does not prevent all forms of discrimination. The clause allows for certain types of legal discrimination when there is a legitimate state interest and the law is structured to achieve that interest in a reasonable manner.
For instance, age restrictions on smoking, drinking, and driving are designed to promote public health and safety, which are considered legitimate state interests. Similarly, admission policies at public colleges may aim to maintain academic standards and ensure student preparedness, reflecting a legitimate interest in educational quality. Such policies must also be rationally related to the interest. This is assessed under what's known as the rational basis test, the most lenient form of judicial review. If a law or policy can be shown to have a rational link to a legitimate government purpose, it is likely to be upheld despite treating different groups of people differently.
To summarize, although the equal protection clause seems to suggest uniform treatment, the law recognizes that practical distinctions among different groups can be rational and serves important governmental objectives. Therefore, various forms of legal discrimination are permissible when they meet certain legal standards and serve significant state interests.