If you take £7.80 from someone by deception, you’ll need a good explanation. If you take £7.8 million from the population by deception you’ll need a good lawyer.

In a recent television interview, Michael Grade, ITV’s executive chairman, said that the deceptions perpetrated on television viewers by programme makers had to be understood by looking at their motives in wanting to produce programmes that worked well. In this area of criminal law, though, motive isn’t relevant to the question of whether a serious crime has been committed. If you rob a bank, the fact that your motive was to get money to pay for medical treatment for someone you love won’t make the police turn away and get on with other work.

Criminal law prohibits various types of conduct like assaulting people, rape, murder, theft, and gaining wealth by deception. Motives, though, aren’t relevant in considering whether a defendant is guilty or not guilty. As Mr Justice McCullough said in a case in 1983: “motive and emotion are alike irrelevant in criminal law”.

For many crimes, the law requires the prosecution to prove that the defendant had a certain frame of mind, such as intention or recklessness, in carrying out a prohibited act. Motive is different. Suppose someone burns down a warehouse. His motive might be that he wants to make a false insurance claim or to mark his hatred of the warehouse’s goods. But whatever his motive, his intention was to torch the place, and that means he can be convicted of arson.

Motive is also irrelevant in deciding whether all sorts of civil laws have been broken. Someone who breaches a contract with you in order to do a better deal with someone else can’t argue in defence that they had a good motive in wanting to keep their business buoyant and preserve jobs. Their motive is immaterial. It’s still a breach of contract.

The general irrelevance of motives can also be seen in the fact that having bad motives in what you do doesn’t alone make something a criminal or civil wrong. You might have a despicable motive to ruin someone by publishing nasty things about them out of sheer malice but if what you say is true then you will have committed no legal wrong.

Nothing that you’re allowed to do legally can become unlawful just because you do it with a bad motive or even maliciously. A case in 1895 arose from a quarrel between a landowner, Mr Edward Pickles, and the borough of Bradford. Mr Pickles wanted to dig a tunnel under his land in order, he said, to drain beds of stone. The local authority said this would divert water from the springs used for its waterworks, and that Mr Pickles real purpose was to force the authority to buy him out.

The House of Lords ruled that an owner of land containing underground water, which percolates by undefined channels and flows to the land of a neighbour, has the right to divert the percolating water within his own land and deprive his neighbour of it. If what you do is legal, then why you do it doesn’t matter.

There are, though, a few parts of law where motive is important. For example, following a verdict of “guilty”, the motives of a criminal might sometimes be relevant when a court is considering how to sentence him.

Motive can also be relevant in cases of judicial review. Decisions made by public bodies, or governmental people can be reviewed by the courts and declared unlawful if they resulted from an improper motive. In 1990, the High Court ruled that Derbyshire County Council had been motivated by bad faith or vindictiveness in deciding to move its teaching advertising from The Times Educational Supplement to The Guardian after a paper from the same group as the TES published an article critical of the council leader. Derby said the change was for educational reasons but the court disagreed — The Guardian was read by fewer teachers (84,000) than the TES (235,000).

And there are a few instances where a motive can worsen an offence. It’s a crime to assault someone by punching him. But the same level of assault becomes much worse if the motive is to punish a witness for the evidence he gave. That’s a contempt of court. An assault, whose motive is racism, or hostility to a victim’s sexual orientation or religion, is an aggravated assault and will be punished more severely than the same assault committed without such a motive. In 2003, in Hampshire, a youth broke a kebab shop window having used the expression “bloody foreigners”, and on appeal it was ruled that this could amount to racial aggravation of criminal damage.

In law, motives which society deems bad, such as racism, can count against someone. But, while bad things are set in defined legal lists, good things are not. We have quite diverse ideas about what is good, and these can’t be used in court by people who want to annul a legal wrong by arguing it was motivated through good. The law is much better suited to banning badness than to giving ground for goodness.

Professor Gary Slapper is Director of the Centre for Law at the Open University

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