Even if no accident occurred, a driver who was tested in this jurisdiction with a blood-alcohol level of 1.75mg would face a mandatory driving ban and would be lucky to walk from court without a custodial sentence.
It is a level far in excess of any reasonable definition of what is safe for a driver.
Ireland's legal blood-alcohol limit is 0.8mg (i.e., 0.8mg of alcohol per 100 millilitres of blood) as opposed to 0.5mg in France. It was lowered from 1.0mg in 1994 in a move that was resisted from many quarters but supported by the AA.
How much drink is needed to get a man's blood level that high depends greatly on the individual. Such factors as weight, metabolism, drinking habits, levels of fatigue and fitness all have an influence.
But suffice to say that it is an incredible amount. You cannot get that drunk by accident.
Even at levels below the legal limit, alcohol affects driving performance very quickly. One of the first things to suffer is reaction time.
Alcohol also diminishes the eye's ability to see light at the red end of the spectrum preferentially. This means that night vision suffers. Gardai will tell you that drunk drivers break red lights. That is not just because they are drunk but because they actually see red less clearly.
Over-confidence is another effect. Last year the AA commissioned a video on drink-driving. We took a group of people down to Mondello Park and set them a series of driving skills tests in controlled conditions, first while sober and then after varied amounts of alcohol.
The test results were unambiguous enough to leave this observer absolutely convinced. All of the drivers failed their test the second time around and all were astonished at how badly they did.
Quite good drivers who had competently stopped the car before our obstacle of cardboard boxes now roared through, overshooting by a car-length or more. Others stopped five yards short, misjudging hopelessly.
Bad enough as our group were, not one of the participants had a blood level approaching that of Princess Diana's driver on Saturday night. They also used ordinary road cars. Diana travelled in a Mercedes S series car - a magnificent machine.
This executive luxury vehicle (as Andrew Hamilton pointed out yesterday) is about twice the weight of an ordinary Ford Escort. In that type of car you can cruise tranquilly down the motorway listening to the radio and not notice until you glance at the speedometer that you purred past the 100m.p.h mark in air-conditioned near silence.
Features like ABS make the car a very safe one in most circumstances. However, it is easy to imagine the fierce speed, the distraction, the arcade-game like dash into that tunnel.
A 1.75mg level means that you have very little chance to control the car in an emergency. If the speed is as high as the 200 kph (125 mph) which some reports have mentioned, little chance becomes no chance at all.
Conor Faughnan is public affairs manager for the AA