Democracy need not, as the adage goes, always die in darkness. These days, the surgical light of a courtroom does the trick.

Marine Le Pen, the right-wing frontrunner to become France’s next president, has just been barred from holding office for five years after being convicted of embezzling EU funds to pay party staff.

The ruling, delivered by a French court on Monday, is the latest — and most explosive — entry in a growing genre: populists blocked from power not by voters, but by unelected judges.