A judge has taken the unusual step of opening a family judgment with a letter to a 14-year-old boy at the centre of the custody dispute.

Mr Justice Peter Jackson, in A Father v A Mother and Stepfather and a Young Person, read the letter to the boy, known as 'Sam' in the published judgment, to his parents and handed it to Sam's solicitor to give to and discuss with him when he returned from a school trip.

Jackson told Sam it was a pleasure to meet him. 'This case is about you and your future, so I write this letter as a way of giving my decision to you and your parents,' he wrote. 'When a case like this comes before the court, the judge has to apply the law as found in the Children Act 1989, and particularly in section 1. You may have looked at this already, but if you Google it, you will see that when making my decision, your welfare is my paramount consideration - more important that anything else.'

He continued: 'When I was appointed a judge, I took the oath that every judge takes to apply the law in a way that is fair to everybody. Some people will say that this or that decision isn't fair, but that's usually their way of saying that they don't like the decision. People who like decisions don't usually say they're unfair.'

The judgment states that there have been court orders since Sam was one year old. Jackson believed Sam had brought proceedings 'mainly as a way of showing your dad how much you love him. It was mainly to meet his needs, and not yours'.

Jackson respected Sam's views 'but I don't take them at face value because I think they are significantly formed by your loyalty to your father'.

Insisting the proceedings must end, Jackson said they had been 'extremely stressful' for everyone. 'This is the fifth case there has been about you and, unless something pretty extraordinary happens, it should be the last,' he added.

Jackson dismissed the father's application to take his son to live in Scandinavia and for the boy to apply for citizenship. He acknowledged the order was not one Sam wanted him to make, 'but I am confident that it is the right order for you in the long run. Whatever each of your parents might think about it, I hope they have the dignity not to impose their views on you, so that you can work things out for yourself'.

Jackson concluded: 'Lastly, I want to tell you that your dad and I enjoyed finding out that we both love the film My Cousin Vinny, even if it might be for different reasons. He mentioned it as an example of a miscarriage of justice, while I remember it for the best courtroom scenes in any film, and the fact that justice was done in the end.'

This is not the first time Jackson has attempted to deliver legal language in a form children can understand: last year be became the first judge to include emojis in a judgment.