What level of judicial scrutiny is used to consider the Constitutionality of laws which classify based on protected classes or fundamental rights?

When laws classify based on protected classes, such as race or national origin, or infringe upon fundamental rights, courts apply "strict scrutiny." This is the highest level of judicial scrutiny, requiring the government to prove that the law serves a compelling state interest and is narrowly tailored to achieve that interest. In contrast, laws that classify based on less sensitive criteria may be evaluated under "intermediate scrutiny" or "rational basis" review, depending on the nature of the classification.