Shortly after I joined the Financial Times in 1986, the Guinness affair exploded. The company had offered financial inducements to associates to support its share price during the takeover of Distillers, another beverage company. The chief executive and two others went to jail.

I have followed many corporate scandals since: banks mis-selling financial products, drug companies hiding adverse research results and bribing doctors, dodgy accounting, Libor manipulation.

Even amid this list of shame, Volkswagen’s use of sophisticated software to detect when its diesel cars were being tested, and to spew out illegal levels of nitrogen oxides when they were not, is striking in its apparent villainy. Most corporate scandals follow one of three patterns. The first is that the law is unclear. Many have been testing its boundaries, and those who are finally blamed, fired or jailed either went too far or were selected by prosecutors or regulators to be made examples of.

The Guinness affair fell into this category. As Richard Lambert, later the FT’s editor, wrote then, there were “grey areas between the boundaries of the law and accepted City practice” and the actions of those arrested “were not so different from those which had earned them plaudits and rich rewards in other times”.

Some, but not all, accounting scandals fall into this category too. Accounting is not an exact science and clients may be desperate for a slight extension of what the auditor accepted last year. The stretching goes on until the company collapses and the auditors are, humiliatingly, fined.

The second category of scandal is where the miscreant company sells customers something that does not help them, or hurts them. The company doing the selling rationalises that it is really up to the customer to decide whether they want to buy it or not. Some of the financial service mis-selling fell into this category, although some involved outright deception.

The third category of scandal occurs because “everyone is doing it” and your company will suffer if you do not. This covers everything from possibly legal but reputation-damaging manoeuvres such as routing profits through low-tax jurisdictions to crass immorality such as covering up adverse drugs trials and criminal activities such as Libor-rigging and bribe-paying.

If we do not do it, when everyone else does, the justification goes, we, our employees and our shareholders will all be worse off.

Assigning malpractices to these categories does not excuse or justify them in any way. But it helps to explain how they happen.

There are few outright crooks in business. Most people who end up doing wrong drift into it. They push the limits and then, when that year’s sales target is a little out of reach, they push a little more.

Their misbehaviour is adjacent to their previously acceptable behaviour and, when the regulator levies a huge fine, or the police arrive at the door, it takes some time, thinking back, to identify the moment when they crossed the line.

What is startling about the Volkswagen affair is that it does not appear to fit into any of these categories. There was no grey area. The law set an emissions limit, and the VW models, when they were on the road, exceeded them.

The company covered this up with an algorithm that reduced emissions to legal limits during testing. VW’s behaviour also did not fall into the category of letting the customers decide. The customers were as deceived as everyone else.

As to the third category, was everyone doing it? We will have to see what emerges. But while other manufacturers may have been gaming the emissions regime by, for example, recharging batteries before testing, so far no other company has been found to have used VW-type “defeat devices”.

Devising a system to detect when a car is being tested surely required planning, expertise and a specific decision. It must have required forethought. It is not something you can drift into through incrementally deteriorating behaviour. We will find out more about who at VW was responsible and why they behaved as they did through regulatory inquiries, class action suits, and — surely — criminal prosecutions.

All corporate misbehaviour is reprehensible. But VW’s has taken us into different territory.

Financial Times