Again, the plaintiffs choose the argument. They choose to use a statute, 42 U.S. Code § 1983, that starts:

> Every person who, under color of any statute, ordinance, regulation, custom, or usage, of any State or Territory or the District of Columbia, subjects, or causes to be subjected, any citizen of the United States or other person within the jurisdiction thereof to the deprivation of any rights, privileges, or immunities secured by the Constitution and laws, shall be liable to the party injured in an action at law [...]

and what they said they had been deprived of is their substantive due process rights.

The plaintiffs brought a Constitutional argument. The court ruled on the Constitutional argument.