Learning disability charity Cornerstone said it was "looking very carefully" at the suggestion by the Prime Minister's wife, who is a barrister specialising in human rights law, that failure to deliver full cost recovery could be a breach of the Human Rights Act.
Last month, the Scottish charity withdrew from a contract with Aberdeen City Council after it cut fees to £11.50 an hour.
On a visit to Cornerstone, Booth told its chief executive, Nick Baxter, that the Human Rights Act placed a duty on public bodies to consider the implications for vulnerable people when taking decisions about funding.
"We will have to think about what she said and pay attention to that in our correspondence with local authorities," said Baxter.
Elaine Motion, head of litigation at Edinburgh law firm Balfour & Manson, who has successfully taken underpaying local authorities to court on behalf of charities, did not rule out success. "It's an interesting argument," she said.