Sinn Féin support a policy of "critical engagement with the EU", and have a "principled opposition" to a European superstate. It opposes an EU constitution because it would reduce the sovereignty of the member-states. It also criticises the EU on grounds of neoliberalism. Sinn Féin MEP Matt Carthy says that the "European Union must become a cooperative union of nation states committed to working together on issues such as climate change, migration, trade, and using our common strengths to improve the lives of citizens. If it does not, EU disintegration becomes a real possibility." The party did, however, support continued UK membership of the European Union in the UK's 2016 EU referendum.