This article argues that the law governing transfer of allowances within the EU Emissions Trading System (EU ETS) should place greater weight upon transactional (and environmental) integrity, even over market liquidity. More broadly, it reflects on the role played by registries in sharing or concealing information about the material world. Although property rules enable market activity through the creation of an abstract carbon commodity, they must also link past to future entitlements in a just way. In emissions trading markets, justice in private transactions is intimately connected to public questions of environmental justice. [---]