A politician being accused of lying is not exactly newsworthy. But a politician being summoned to court to answer a criminal charge for lying — or, “misleading the public by endorsing and making statements about the cost of European Union Membership, which he knew to be false” — certainly is.

The country in question is the United Kingdom, the politician is Boris Johnson (former foreign secretary and ardent Brexiteer), and the allegedly fraudulent claim is the one that appeared on the Vote Leave’s bus campaign: that Britain sends £350 million a week to the EU when it could be spending this money on its National Health Service instead.

Although there are mixed views about the accuracy of the Leave slogan, this is beside the point. After more than £200,000 was raised through crowdfunding, a private prosecutor brought forward a charge of misconduct in public office. In a statement, Johnson’s defense remarked that:

The application represents an attempt, for the first time in English legal history, to employ criminal law to regulate the content and quality of political debate. That is self-evidently not the function of criminal law.

Quite so. Dragging politicians to court in this way sets a dangerous precedent both for the future of free speech in British politics generally, and for individuals who find that — whether they are right or wrong — their enemies have deeper pockets.