“Even more disturbing, the seizures do not appear to be part of any criminal case. If they were, then perhaps an argument could be made that the seizures were similar to a seizure of physical property as part of a criminal investigation.”

Let’s be Devil’s advocate here. Let’s say you have a stash of cocaine. The police seize it, but choose not to prosecute you.

Does the mere choice of whether or not to prosecute impact the validity of the seizure? I think the issue of authorities not prosecuting is the tail, with the actual seizure being the dog.

Ir does seem that in either case (domain names or cocaine) the parties from who the goods were seized have the option of filing a lawsuit for return of the goods.

I’m certainly not an expert on criminal law, though :)