Many more inquests in England and Wales are likely to conclude that a suicide has taken place after three senior judges ruled that the standard of proof when it comes to deciding if a person had taken their own life should be lowered.

The landmark ruling is likely to cause controversy and deep upset among some community and religious groups for whom the idea of suicide carries a deep stigma.

Previously, coroners and juries had applied the criminal standard to suspected suicides, meaning they had to be “sure” that someone had taken their own life.

But three appeal court judges ruled on Friday they could apply the civil court standard and only had to be satisfied that it was “more probable than not” that someone had deliberately killed themself.

The ruling follows the death of a man called James Maughan, who was found hanging in a cell at a prison in Oxfordshire. After hearing the case, the Oxfordshire coroner, Darren Salter, decided there was not enough evidence for the jury to be sure he had intended to kill himself so they could not reach a blunt “short form” suicide conclusion.

However, Salter gave them the chance to write a longer narrative conclusion that, on the balance of probabilities, Maughan had taken his own life. The jury did this and came to the conclusion it was more likely than not that he had intended to kill himself.

A member of Maughan’s family disputed the result, arguing the coroner was wrong to advise the jury that they could effectively return a suicide verdict.

He took the case to the high court, which ruled, unexpectedly, that the standard of proof for suicide should be the balance of probabilities. The case was taken to the appeal court, which has backed the high court judges.

The three appeal court judges studied years of authorities, from practice guidance issued by the chief coroner to statements made in the leading textbooks on the law relating to coroners.

Lord Justice Davis said: “I conclude that, in cases of suicide, the standard of proof to be applied throughout at inquests, and including both short-form conclusions and narrative conclusions, is the civil standard of proof.”

Davis acknowledged that the conclusion that Maughan had killed himself was distressing for his family as they held strong Catholic beliefs. He quoted a statement from Catholic deacon David Palmer that “indicated the teaching of the Catholic church is that suicide is contrary to love for the living God and is considered a grave sin”.

Lord Justice Underhill said: “I think it is a pity that the law in this area has been left to develop piecemeal in the way that it has, and I … would see value in it being authoritatively stated in the coroners’ rules.”

Georgina Wolfe, a barrister at 5 Essex Court, said: “In future, it will be much easier, and thus more common, for coroners and juries to reach suicide conclusions.

“Many families who have lost loved ones will not welcome this development. As the courts have noted, suicide still carries a stigma within some religions communities and there can be financial implications, too. But, for those working in mental health and suicide prevention, a likely increase in the numbers of suicides recorded may help to persuade the government to dedicate more funding to this important work.”

However, the judges did not agree that the standard of proof at an inquest should be the same for unlawful killing as suicide.

Gus Silverman, a inquest lawyer at Irwin Mitchell who specialises in death in custody cases, said: “In the context of deaths in custody, this judgment means that coroner’s courts will apply a lower standard to determining whether a person meant to take their own life than when determining whether they were unlawfully killed, for example as a result of police restraint. It is to be hoped that the supreme court will address this imbalance.”