Decision-makers in ancient civilisations sought answers from an oracle, an infallible authority who gave wise counsel. The most important, the Delphic oracle, reputedly fell into a trance and spoke in riddles, which were interpreted by priests. In the modern European Union the oracle is the European Court of Justice. National courts seek its wise counsel, but sometimes it appears to work in unfathomable ways.

Last December the court struck a heavy blow against “social Europe” – the concept of a Europe that treats its workers and poorer citizens fairly – in a landmark judgment on the so-called Laval case, concerning Latvian workers on a Swedish building site.