National efforts will be assessed against the objectives laid out in the NDCs, but the NDCs themselves will not be assessed by the UNFCCC for adequacy.6 Therefore, no Party can rely on its membership in the Agreement and good-faith fulfilment of its NDCs to shield it from being judged to be ‘inadequately’ pricing carbon, and being subject to BCA as a result. See, for example, UNEP (2015). It has been proposed a number of times and has consistently been rejected in the legislative or regulatory process.