I used to date a guy who had a prosthetic arm which had various attachments - a hook, a hand and a ball and socket thing to assist with driving. He told me at the time that as the prosthetic is a replacement body part, they weren't allowed to take the prosthetic away if he ever landed in prison. The hook always looked dangerous so I was a bit surprised at that info but if he used the hook as a weapon, that could then be taken away but it would be replaced with the hand attachment. This is in the UK though so I was a bit surprised when Abu Hamza had his hooks taken off him when he was extradited to the USA as I thought they'd be the same regarding prosthetics.