I have also thought in the past that this would be an excellent policy to be added to the WTO treaty. It seems like a basic, necessary clause that signatories

I have also thought in the past that this would be an excellent policy to be added to the WTO treaty. It seems like a basic, necessary clause that signatories would be happy about since it protects against product dumping by ultra-polluting countries. There is probably some aspect of it that makes it too hard, such as enforcement. But most of the WTO isn't enforced anyway. Typically companies sue their national government to force them to take action under the WTO; at least this is what happens with manufacturers in the U.S.