among other things it involves the implementing party s unilateral judgment that the foreign party is not doing enough to price carbon embedded in traded goods it is not clear how the principle of common but differentiated responsibilities might be properly respected in the course of such a judgment in addition the choice of methodology for assessing the carbon content of a given imported product is not straightforward cosbey et al there is no consensus on the wto legality of bca most analysts conclude that the detailed design of the mechanism would be determinative cosbey et al the agreement does not involve consensus on the adequacy of each parties efforts in the same way that for example the kyoto protocol arguably did in its first commitment period there was no negotiation process that focused on the level of ambition of the various ndcs