A strongly critical blog post written by Jay Kennedy, director of policy and research at the training and publishing charity, accuses the regulator of becoming "increasingly unmoored from its various statutory duties" since the Conservative peer Baroness Stowell took over as chair of the commission early last year.
He says the regulator has become overly concerned about public confidence in charities above its other duties and says even specific regulatory actions taken by the commission "are framed by and for the headlines, with the commission acting as kind of self-appointed crusader for what the public wants rather than an objective assessor of the facts, context, data and evidence".
Kennedy says the regulator has taken an "insufferably patronising, moralising, hectoring, lecturing tone" towards the sector.
"As if hundreds of thousands of experienced and committed trustees, volunteers and staff are naughty children who need to be taught the error of their ways," he says.
He says the notion of public benefit has become about "delivering maximum benefit in a way that is compatible with what charity means (read: not be controversial, overly commercial or ‘political’)".
He says: "Compliance includes being seen to bend with the prevailing wind when scandals erupt (read: not defending the charity’s reputation or rebutting flawed accusations), rather than judicious enforcement of legitimate regulatory procedures and processes.
"This mission drift has perhaps been most confused around public benefit, an historically contested (and confusing) but real concept in charity law.
"The commission’s leadership now seems to be conflating it in practice with ‘public opinion’ and ‘public expectations’, neither of which have any legal basis at all as far as I can tell.
"The supremacy of these terms in the current narrative signals an extraordinary power grab over the rights and autonomy of people who set up, support and govern charities, by a regulator that is basically making up new rules as it goes along."
Kennedy adds: "This is a road to hell. Not just for charities, but the regulator too – and ultimately society.
"Under Stowell’s leadership, the regulator is rapidly losing the trust and confidence of the sector it regulates.
"People are tuning out; waiting for the leadership to change; no longer engaging; some are even starting to push back and make plans to resist. They’re sick to the back teeth of being patronised."
He says the regulator’s leadership "seems unable or unwilling to grasp" that it needs the respect of those it regulates and this respect is ebbing away.
"The commission is under-resourced but also vastly outnumbered by the number of charities, and relies upon the goodwill of hundreds of thousands of volunteer trustees who try to do their best," he says.
"If it throws that goodwill away in favour of the bully pulpit and trial by media, then trusteeship – the lifeblood of the sector – may become a burden too big to bear for many."
The Charity Commission declined to comment.