For most people who have obsessive interests, these run to no more than compulsive DIY, recording the numbers of railway engines, collecting stamps or similar harmless pastimes.

Unfortunately, the compulsion of some people is not so benign, even if their behaviour is legal. For lawyers and their clients, few can cause such disruption as the serial litigator or ‘vexatious litigant’.

A vexatious litigant is someone who becomes convinced about the rightness of their cause as regards some legal matter and determines to pursue it through the courts no matter what the cost to them or the hapless subject of their suit.

Despite rebuff after rebuff in the courts, they will seek to renew their action or start new actions to prove the correctness of their position, no matter how frequently they are advised that their case has no merit. They will normally claim that ‘it is a matter of principle’ or that they must take action to prevent their being victimised in some way by the unfortunate target of their misguided ire.

Frequently, the vexatious litigant will start many actions against a variety of people, making numerous allegations and causing considerable unnecessary distress and expense.

Fortunately, in the UK, the Attorney General has the right to petition for an order banning the vexatious litigant from carrying out litigation and from acting as a ‘litigation friend’ for others. A litigation friend is a person who acts for someone else (a child or someone who lacks mental capacity to act for himself). If the petition is granted, an order will be made banning the person from issuing proceedings in the courts in England and Wales without the permission of the court.