Yvonne Hossack has represented more than 30,000 people across the UK
A solicitor from Northamptonshire involved in campaigns to keep care homes open breached rules of conduct for her profession, a tribunal heard.
Yvonne Hossack, from Kettering, behaved in inappropriate ways, the Solicitors' Disciplinary Tribunal was told.
Miss Hossack is accused of six breaches of rules governing solicitors' conduct, including providing confidential information to third parties.
Miss Hossack, who is 53, denies all the allegations against her.
Jonathan Goodwin, for the Solicitors' Regulation Authority, told the hearing in London: "This case is not about whether Miss Hossack is a caring individual.
"It is evident that she cares.
"The issue in the case is whether the way in which she has conducted herself in certain identified respects was appropriate or not."
He said there were three main areas in the allegations relating to Miss Hossack - the receipt of full and proper instructions, client confidentiality, and conduct of litigation.
He also claimed she had breached the confidentiality of eight clients in a letter to the General Medical Council (GMC).
She said she had done this "in the utmost good faith".
Miss Hossack also had an "inappropriate approach to litigation", Mr Goodwin said, giving examples of various proceedings she had started.
Miss Hossack said: "I did not reveal confidential information to the GMC lightly."
The tribunal continues.