The European Commission proposed a legislation to bring the aviation sector into the European Union's pioneering emissions trading scheme (EU ETS) in order to control the rapid growth of CO2 emissions from air travel. Until 2008 airlines were not subject to the constraints on energy consumption or greenhouse gas emissions that other businesses have to live with. Emissions from domestic flights are covered by the Kyoto Protocol’s emission targets for developed countries, but international aviation – which makes up the vast majority of flights - is not. In addition, jet fuel for international flights has historically been exempted from taxation. Hence the need for policy action.