“How can you act for a man when you know he is guilty?” is the most common question asked of defence lawyers.

Well, for a start, a lawyer doesn't know if a client is guilty or not unless he says so — in which case he or she must refuse to act for the client if he insists on pleading “not guilty”.

Secondly, although a lawyer may have his suspicions, he must keep them to himself. His job is to represent his client to the best of his ability, no matter how bizarre or unlikely the defence he puts up. The recent cases of Steve Wright, the “Suffolk Strangler”, and Mark Dixie, who murdered the model Sally Anne Bowman, throw the spotlight on improbable defences.

In response to overwhelming forensic science and corroborative evidence, Wright’s defence was that it was all a coincidence. Dixie said he’d had sex with a woman lying on the ground before realising that she was dead. Going back further, some of the failed London Tube bombers said it was all a hoax, meant to scare, not to harm.

Why raise do people raise such extraordinary responses to the prosecution case? The most obvious motive is that they might get away with it. Criminal trials can be very technical in the application of rules and practice. There is always a chance that the judge or the prosecution may make an error - thus allowing the defendant off the hook.

It is, after all, the prosecution’s job to prove its case, not for the defendant to have to prove his defence. The Court of Appeal is full of cases where defendants attempt to rely on prosecution mistakes to quash a conviction and, very occasionally they are successful.

Secondly, the jury might buy the story. They have to be “certain so that they are sure” of the defendant’s guilt with any doubt with any crumb of doubt exercised in favour of the person in the dock, as O J Simpson discovered. Thirdly, the defendant may be innocent - no matter how strange the defence.

Does a defendant run any risks fighting a case? Certainly. The court offers a discount for a guilty plea, with the amount depending on how early the plea is entered. Pleading not guilty and being found guilty is likely to attract a more severe sentence than if the defendant had put his hands up to a “fair cop”.

A lot of time, money and energy is put into a case. It’s a sign of a civilised society that everyone has the right to a fair trial, no matter how fantastic the defence may be. That right is also enshrined in Article 6 of the European Convention on Human Rights. The best we can do is put our faith in the system and hope that that justice is served. Remember, both Steve Wright and Mark Dixie were found guilty.

Stephen Gerlis is a District Judge at Barnet County Court

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