There’s a broad mainstream consensus on both sides of the Atlantic: Trump’s tweet telling four hard-left minority Congresswomen to ‘go home’ to the crime-ridden countries they’re from, when three of the four were born in the US, was racially inflammatory and staggeringly ill-judged.  But the first question that would be raised in the UK if a British politician committed such a gaffe is the last question raised in the US: was that post ‘hate speech’?

The First Amendment to the American constitution guarantees five basic freedoms, including freedom of speech, and these principles ought rightly to pertain in other democracies such...