Donald Trump loves to disregard political rules. Now he is trying to break yet another: although it has long been customary for American presidential candidates to release their tax returns, Mr Trump is refusing to comply.
He says this is because these need to be audited by the Inland Revenue Service; critics say he has something to hide. Either way, the row is becoming poisonous — not least because polls suggest that two-thirds of Americans think he should release those returns.
As the mudslinging intensifies, it is not just the issue of Mr Trump’s tax returns that should make American voters angry. The bigger scandal is the way the corporate tax code treats those who own or develop real estate, and construction groups in a wider sense.