Why would Congress pass legislation saying that it's not allowed to amend trade agreements? Why don't they just not amend trade agreements?
That Congress?
Also, we rewrite the Constitution because Amendments allow us to. It's just that we do it so fast and then change it back that you don't even notice.
I really do not know.
OTOH - the mainstream media is not reporting on this at all. Doing a search for 'trans pacific partnership' on CNN - the first result is a story about the G-20 Summit on Jul. 15th.
The more you look at, investigate and try and understand this story the crazier you may seem to other people.