a. Equal protection/semi-suspect: First, mid-level review will be used to judge an equal protection claim, where the classification being challenged involves a semi-suspect trait. The two traits which are considered semi-suspect are: (1) gender; and (2) illegitimacy. So any government classification based on gender or illegitimacy will have to be “substantially related” to the achievement of some “important” interest.
b. Contracts Clause: Second, certain conduct attacked under the Obligation of Contracts Clause will be judged by the middle-level standard of review.
c. Free expression/non-content-based: Finally, in the First Amendment area we use a standard similar (though not identical) to the middle-level review standard to judge government action that impairs expression, but does so in a non-content-based manner. This is true, for instance, of any content-neutral “time, place and manner” regulation.