In Switzerland like in many other countries, political decision makers face the two-fold challenge to adapt current electricity market regulation to achieve different goals at the same time: market liberalisation and sustainable development. The general trend of the liberalisation of the electricity markets implies radical structural changes of the electricity industry as well as of the institutional rules for its regulation. But how can the overall goal of sustainable development be brought in line with the ongoing discussion on market (de)regulation? After reflecting on the objectives of the liberalisation process, we analyse the political acceptance of different instruments to achieve environmental goals in a liberalised electricity market; the analysis is based on empirical data from an inquiry among 250 key players of Swiss energy policy. We compare these outcomes to theoretical (economic) insights on 'first-best', 'second-best' and 'third-best' solutions, and we conclude with a closer look at perspectives for a future energy supply structure in Switzerland.