There has been intensive talk and agony over the shape of the Irish border post Brexit.
The issue has in fact almost led to a collapse in the Brexit talks.
Yet again and again the point needs to be made that there is already a border.
There is a border for VAT and fuel and alcohol duties, and for taxation overall.
In fact a whole body of laws change at the border.
The people who know this most of all are smugglers.
For more than a decade, the News Letter has been reporting and commenting on the lenient way in which fuel duty is policed near the border. For many years the media was informed by the authorities about fuel plants that had been dismantled, but there were few arrest and next to no charges.
That has changed in recent years.
It has now emerged that an HMRC investigation has led to the dismantling of a fuel laundering plant in south Armagh with the capacity to produce 20 million litres of illicit fuel a year.
The HMRC operation led to people being arrested in Belfast and England.
That investigation will take its course.
It is possible now, however, to talk about the wider issue.
As Tracey Noon, assistant director, Fraud Investigation Service, HMRC, says: “The illicit trade in laundered fuel is a serious crime and one we are determined to detect and disrupt.”
Fuel duty is not only very lucrative to the cheats who engage in it, it is costly to the government.
Money that should be available to spend on roads and schools and hospitals and other services, including indeed, investigating forces that maintain law and order, is kept from the Treasury and so from those public needs. Not only that, the evasion is unfair on the great bulk of the population, who have to pay very high rates of fuel and alcohol duty.
It is good, therefore, to hear the authorities talk about seriously they take it.