Does Tennessee's Serious and Violent Sex Offender Monitoring Pilot Project Act, which requires convicted sex offenders to wear a GPS device (including those previously convicted), violate the Constitution's ex post facto clause? Six judges on the U.S. Court of Appeals for the Sixth Circuit thought so, and dissented from the denial of en banc review of a panel decision concluding otherwise. Wrote Judge Keith for himself and five other judges:

I believe that the retroactive application of the Surveillance Act constitutes an Ex Post Facto Clause violation because (1) as a catalyst for public ridicule, it is a form of shaming, humiliation, and banishment, which are well-recognized historical forms of punishment; (2) it promotes the traditional aims of punishment; and (3) it is excessive in forcing Doe to broadcast his sex offender status not only to those who choose to inquire, but also to the general public. The majority, in upholding the Surveillance Act, deliberately turned a blind eye to the obvious effects of forcing Doe to wear such a large box on his person. Moreover, the majority erred in its emphasis that such boxes "will only become smaller and less cumbersome as technology progresses." The question at hand was whether the required technology under the Surveillance Act violates the Ex Post Facto Clause today, not whether technology could conceivably develop such that it will become inconspicuous in the future.

UPDATE: Here is the original panel's decision in Doe v. Bredesen.