In order for a law to violate the Constitutional prohibition against Ex Post Facto laws, it must be (a) retroactive, and (b) punitive.
In 2018 the Village of Hartland, Wisconsin decided it had too many registrants living in it’s village, so it created a moratorium on “the establishment of “Temporary or Permanent Residence” by a “Designated Offender,” within the Village” In other words, until the concentration of registrants dropped, they wouldn’t let any more move in.
A registrant who wanted to move to Hartland in order to live closer to work and family sued the Village, asserting that it violated the Ex Post Facto Clause the Constitution. The district court held that the law was not retroactive because it applied to registrants who prospectively wanted to move into the town. Because the district court determined the first prong of the test didn’t apply, they didn’t proceed to determine whether it was punitive.
The registrant appealed, arguing that it related to his past conviction and therefore was not prospective, but retroactive. The 7th circuit court of appeals agreed. They even applied Smith v. Doe (for good reason this time), by saying, “The Court has also implicitly acknowledged, in Smith v. Doe, 538 U.S. 84 (2003), that sex-offender laws applying to people with convictions before the effective date are retroactive.”
Having now ruled that it passes the first prong (it is retroactive), they sent it back to the district court to determine whether it’s punitive.
You can read the decision here: https://all4consolaws.org/wp-content/uploads/2022/08/Koch-v-Village-of-Hartland-7th-Cir-Ex-post-facto-Aug-2022.pdf