In Employment Division v. Smith, Justice Scalia identified the concept of hybrid rights: a restriction that targets two constitutional rights would be reviewed with heightened scrutiny. For example, a ban on saying "Merry Christmas" would offend both the freedom of speech and the free exercise of religion. The hybrid rights doctrine was a useful way for Justice Scalia to distinguish the outcome in Smith with earlier free exercise clause cases that applied heightened scrutiny. Yet, this doctrine never quite caught on in the Free Exercise context.
Still, the hybrid rights doctrine always made sense to me as a logical matter. Sometimes the whole is greater than the sum of the parts. Even if individual features of some policy are barely constitutional, when those features are combined, the policy becomes unconstitutional. The Court employed this reasoning in Free Enterprise Fund, in which the two layers of insulation triggered a violation of the Appointments Clause.
In two recent separation of powers cases, the Fifth Circuit adopted this sort of combination logic.
