Should the US government follow the rules when it comes to treatment of terrorism suspects?

Of course but the reality is that when the US government agrees w. particular terrorists like the IRA they can't seem to give them enough funding and support. You have to suspect that any government that was started by a guerrilla movement of revolutionary terrorists fighting their own mother country for home rule aren't going to be too bothered about observing international rules. The US would be like Canada, NZ or Australia if it did and no terrorist menace on the scale they have 'developed' would exist.