The founding document of the European Union, the 1957 Treaty of Rome, promised – among other things – “a system ensuring that competition in the common market is not distorted”. Preventing the abuse of state aid is a core part of the EU’s original mission.

So the European Commission must assert its authority, becoming actively involved as an arbiter in the negotiations regarding the sale of Opel, the rump of General Motors’ European operations, where decisions are being determined amid volleys of subsidies by EU national governments.