A more thorough explanation:

Definition: A fortiori is a Latin term that means 'from [the] stronger'. It is used to signal an argument that is based on an even stronger argument. This suggests that the argument is so strong that it is unanswerable. However, the argument a fortiori can still be challenged by questioning whether the conclusion can truly be drawn from the stronger argument.

Example 1: In Bobby v. Van Hook, the court held that “what the Supreme Court has said of state requirements is a fortiori true of standards set by private organizations.”

Example 2: In Richmond v. J.A. Croson Co., the court held “that Congress may identify and redress the effects of society-wide discrimination does not mean that, a fortiori, the States and their political subdivisions are free to decide that such remedies are appropriate.”

These examples illustrate how a fortiori is used to make an argument stronger. In the first example, the court is saying that if something is true for state requirements, then it must be even more true for standards set by private organizations. In the second example, the court is saying that just because Congress can address discrimination, it doesn't mean that states can do whatever they want. Both examples show how a fortiori is used to make an argument more convincing.