The New South Wales (NSW) Greenhouse Gas Redution Scheme (GGAS) in Australia is a baseline and credit emissions trading scheme with the stated aim of reducing the per-capita greenhouse emissions associated with electricity consumption in the state of NSW. Here we provide a detailed assessment of the GGAS design and operation, with a particular emphasis on its effectiveness in delivering physical emissions reductions that would not have occurred in its absence. We find that a number of design features mean a significant proportion of the tradeable 'abatement' certificates are unlikely to correspond to the claimed emissions reductions. While some of these adverse design choices might be corrected, others would seem inherent to the underlying scheme design. Our analysis highlights the major governance challenges with emissions trading approaches and hence the importance of good policy implementation processes including the need for separation of powers through a scheme development process that involves design, assessment and revision. These GGAS lessons would seem relevant for governance with all emissions trading schemes, and has particular implications for cap and trade schemes that incorporate baseline and credit offset schemes, as well as to the 'White Certificate' schemes increasingly being seen as a means of fostering enhanced end-use energy efficiency. (C) 2008 Elsevier Ltd. All rights reserved.