Whenever a court reviews legislation under an equal protection, substantive due process, or free speech analysis, the court considers whether the fit between the legislature's chosen means and intended ends is sufficient to pass constitutional muster. The Supreme Court analyzes these "fit" questions by considering the manner in which the statute achieves its benefits and burdens in terms of whom the statute regulates and whom the statute fails to regulate. Of course, these "fit" questions are different depending upon whether the Court uses minimum rationality review, "heightened" rational review, intermediate review, or strict scrutiny. But in all cases, the question of legislative fit plays a large part in the analysis.
R. R. Kelso,
Considerations of Legislative Fit Under Equal Protection, Substantive Due Process, and Free Speech Doctrine: Separating Questions of Advancement, Relationship and Burden,
U. Rich. L. Rev.
Available at: https://scholarship.richmond.edu/lawreview/vol28/iss5/4