Songwriter Claude Kelly, who worked with Britney Spears on her 2008 album Circus, admits that he thought the troubled singer was being "mistreated" at the time.
The Gimme More hitmaker was placed under a conservatorship - her father Jamie Spears and, at the time, lawyer Andrew Wallet took control of her personal and professional affairs - after her well-publicised breakdown the same year.
Kelly told the Sun newspaper: "The studio we worked at has really high fences and they were climbing the fences and cutting holes through the mesh to get shots of her.
"It was literally mayhem. And she was actually very quiet, very shy and kept to herself.
"What I got was that clearly she had been mistreated and taken advantage of enough that she had a huge wall up."
And Kelly felt that, despite the chaos around her, Spears was "incredibly professional" and focused on her work.
He added: "But what I remember the most is that for someone who had been painted as all over the place, a mess, tragic and sloppy, she was incredibly professional.
"Much like a professional dancer, when it comes to the art, she's a machine. It's everything around her that's insane."
Kelly is concerned that Spears - who has sons Sean 15, and Jayden, 14, with ex-husband Kevin Federline - still being under a conservatorship so many years later throws up wider human rights issues and implications.
He said: "She's 39 and she's been doing this a long time, it doesn't make sense that she's being handled like a toddler who has no rights.
"The whole thing brings up a bigger issue of human rights and it doesn't make sense to remove the right for people to live the way they want to live.
"There's hundreds of other celebrities that have had pretty tough times like public breakdowns, public divorces or embarrassments and they haven't needed to lose all of their rights.
"If that's the case then we should all be worried because we are all going to f*** up, fall short and make mistakes.
"God forbid that someone can come in, whether it's your father or your mother, your husband or your wife or whatever and decide, 'You no longer have the right to decide how you live your life'."
Although the Toxic hitmaker hasn't released an album since 2016's Glory, Claude warned people not to write her off as a has-been.
He said: "Anyone is capable of putting out a great new body of work from her at any time. We're talking about a mega star.
"She's not a has-been. She's a genius at it and you can never, ever, ever count out a brilliant musician like that. She's always a hit away."