If these assumptions are correct, efficiency is achieved regardless of how property rights are allocated. In the case of emissions trading, this suggests that equity and efficiency can be addressed separately: equity is taken care of in the allocation of emission permits, and efficiency is promoted by the market system. In reality, however, markets do not live up to the ideal conditions that are assumed in Coase's model, with the result that there may be trade-offs between efficiency and equity (Halsnæs "et al.", 2007).