The Charity Commission might have to rewrite all of its public benefit guidance if the courts find defects in its guidance on independent schools, charity lawyers have warned.
They argue that if the principles behind a part of the guidance are found to be at odds with the law, doubt would be cast on the guidance as a whole and a complete revision would become necessary.
Last week the Attorney General, Dominic Grieve, asked the charity tribunal to clarify the operation of charity law in the context of fee-charging independent schools.
The case will be considered in the Upper Tribunal (Tax and Chancery) by senior judges with experience of charity law, sitting with Alison McKenna, the principal judge of the charity tribunal.
One senior lawyer, who asked not to be named, said: "If the underpinning principles of public benefit are overturned in the context of this case, it could be that the commission will have to rewrite all of the public benefit guidance."
Rosamund McCarthy, a partner in the law firm Bates Wells & Braithwaite, said: "If the public benefit guidance on fee-charging schools is found not to be in line with the law, it would undermine the commission's integrity as a regulator and leave its other guidance open to challenge."
The Charity Commission has used various guidance that it has published since January 2008 to assess whether sample groups of independent schools, arts charities, care homes and religious charities provide sufficient public benefit to justify their charitable status.
The Independent Schools Council has challenged the guidance on fee-paying charities and has asked for a judicial review. This will be heard next week and could be combined with the Attorney General's reference.
Tom Murdoch, a solicitor at Stone King, said one argument might be that the guidance was wrongly based on an assessment of a charity's activities, rather than its purposes. Another might be that it placed too much emphasis on public benefit related to the stated purpose of a charity and not enough on benefits unrelated to its cause.