The RSPCA and several other large charities are warning that charities will be put off pursuing legitimate inheritances if it loses its forthcoming appeal in the Gill legacy case.
The charity is facing a bill for costs of up to £1m after university lecturer Christine Gill last year successfully challenged her mother's bequest to it of the £2m family farm. Its appeal is expected to begin in the autumn.
Mark Watts, chief executive of the RSPCA, told Third Sector that charities outside the top 200 could be forced to "cave in" when legacies were disputed because of the fear of incurring huge costs.
"My biggest fear is that the threat of costs at that sort of level will put a lot of charities off going down the road of fighting, even if they are justified," he said. "It would be a bridge too far."
In a press statement signed by the Charities Aid Foundation, the Great Ormond Street Hospital Children's Charity and Guide Dogs, the RSPCA said the case was troubling for many charities. "It is crucial that this matter is finally settled, one way or the other, so that charities can be more certain of the legal landscape and can plan accordingly," the statement says.
The case has been contentious because Gill's mother explicitly left the entire estate to the RSPCA. The judge overturned the will after deciding that her late husband had bullied her into making it and that Christine Gill had been led to believe that the farm would be left to her.
Tim Lowth, director of finance and support services at Guide Dogs, said charities should think more about mediation and negotiation on contested legacies before they went to court.
"We'd much rather reach a settlement, and sometimes it's a matter of looking at evidence around the will that might indicate the deceased had actually intended to change the will in somebody's favour," he said. He also called for more guidance from the Charity Commission.
A spokeswoman for the Charity Commission said that when a legacy was challenged, charities should consider the strength of the claim and the cost of defending the case.
"Charities do not have a duty to pursue disputed legacies at all costs, but must make a judgement, balancing the prospects of success against the risks," she said.