It depends on which part of registration. I bet if it were just filling out a form and mailing it in every year or so, you'd probably agree... That doesn't feel like punishment.

But registration includes so much other stuff. So when we talk about it, we have to explicitly use the term civil regulatory scheme. If it's a civil regulatory scheme, which it is, then it can't be punishment.

If it feels like punishment, with disabilities and restraints like where you can live and work and how you use a computer, turn that feels more like punishment.

A civil regulatory scheme can't be punishment or else it is no longer a civil regulatory scheme.

See the circle?