Well this is a really poor article isn't it?
It looks like the concern is about this "civil commitment" thing the Americans have going on.
I had to go and read another website to try to find out what that is because the Telegraph didn't seem to want to burden me with pertinant facts.
http://www.doc.wa.gov...s/civilcommitment.asp
It looks like civil commitment is a process whereby after someone's done his time in prison the state can apply to a court to say that they're still a threat and should continue to be locked up indefinately.
If I've got that right it raises questions about the case - like whether he's actually completed his sentence - if not why is civil confinement an issue?
The matter of continuing to imprison someone after they've served their sentence because you've 'changed your mind' about them is a worrying one - we do something similar with IPP cases but those are sentences imposed at the time of the original court case so are subtly different.