In January 2008, Wheeler brought an action against the government, represented by the Prime Minister, Gordon Brown, and the Foreign Secretary, David Miliband, over the government's process of ratification of the Treaty of Lisbon. The action sought to prevent the government from completing ratification of the treaty, on the grounds that it was illegal for a government to breach the public's legitimate expectation of adherence to manifesto and other commitments. The government, along with the Conservatives and Liberal Democrats, had pledged in their 2005 manifestos to hold a referendum on the European Constitution, which Wheeler holds does not have 'significant or material differences' from the Treaty of Lisbon. This action failed.