Victims of sexual abuse or men who cannot form relationships with women could use the Martin case to justify violence when they feel threatened, lawyers said yesterday.
The Court of Appeal's decision to accept Martin's plea of diminished responsibility could also open the door for defendants with less serious personality disorders to challenge their convictions.
Lord Woolf, the Lord Chief Justice, was convinced that Martin was suffering from a paranoid personality disorder when he fatally shot Fred Barras.
But Malcolm Fowler, former chairman of the Law Society's criminal law committee, warned that householders who identify with Martin might now "latch on" to the case by using it to justify disproportionate violence against burglars or others of whom they feel threatened. "Some people will want to stretch the law. Mischief could flow from this with people arguing 'anything goes when your house is burgled'," he said.
Although Lord Woolf categorically rejected Martin's case for self-defence by making quite clear that the farmer had used unreasonable force in defending his home, Mr Fowler said this might be forgotten in the blaze of publicity that would inevitably follow news of the decision.
The danger, lawyers warned, was that by accepting a plea of diminished responsibility the judges may have given the green light to lawyers to present many kinds of behavioural problems as defences to murder. Mr Fowler said that the law was crucially developed in 1995 at the Sara Thornton appeal when she successfully argued that the killing of her husband was caused by prolonged abuse. The Court of Appeal also reduced her murder conviction to manslaughter.
Yesterday's judgment vindicates Martin's original legal team, led by Anthony Scrivener QC, which was accused of using the wrong tactics during the trial.
Speaking from his home yesterday, Mr Scrivener said he was "delighted" that his former client had had his sentence reduced.
But he said that Martin's refusal to allow him to argue manslaughter at the trial was influenced by Max Clifford's "over optimistic" view that he would win outright if Mr Scrivener defended the alleged murder on the ground of self-defence. Mr Scrivener said that he also commissioned a psychiatric report but it "did not support" diminished responsibility.
Mr Fowler urged lawyers to remember that this case was decided on its own facts, which created no new law. What it did show, he said, was that mandatory sentences should be abolished so that judges were free to use their proper discretion when passing sentence for murder cases.
This view was supported by Norman Lamb, Liberal Democrat MP for North Norfolk. He said: "This sensible decision strikes the right balance as the criminal justice system must place high value on human life. But Tony Martin's case has demonstrated that the mandatory life sentence for murder is not satisfactory."