A study of the EU sustainability criteria has been performed by Serina Ahlgren, f3 coordinator for SLU (Swedish University of Agricultural Sciences). In short, the sustainability criteria are implemented to ensure that biofuels are produced in a viable way and include protection of sensitive land and reduction thresholds of greenhouse gases compared to fossil fuels. The report gives an overview of the biofuel criteria in the EU, and discusses how they work in practice. You can find the report here.