The government can shut down a website and even confiscate the domain name, BUT, they have to have a judge sign the order after they show cause and the judge agrees that it is in the best interest for all concerned.
Or, the government can just shut down a site and then make the owner of the domain go through a process to have it opened back up, but there is no guarantee that it would happen. The request to reopen it, may be denied by a judge, which would force the domain owner to sue and have a jury trial, then the jury would make the determination.