4:10 PM PT -- We got Rosengart outside the courthouse in L.A. Monday shortly after the docs were filed ... he continued to praise the singer for her courage, and vowed he'd continue to fight for her.
Britney Spears and her new lawyer say Jamie Spears has stripped Britney of her dignity, autonomy and fundamental liberties ... and they lay out their case in new legal docs as to why he must be removed as conservator of her estate.
In the new docs, Britney and her attorney, former federal prosecutor Matt Rosengart, claim Jamie has essentially terrorized his daughter, forcing her to get certain treatments and signing off on drug regimens that were allegedly harmful to her.
The docs also challenge Jamie's management of the conservatorship, claiming he's made a king's ransom over the last 13 years. He gets $16,000 a month plus $2k a month for office expenses. He also got 1.5% of the gross revenues from her Vegas residency ... which brought in $137.7 million. The docs say Jamie's cut alone was at least $2.1 mil. The docs go on to say Jamie got $2.95% from Britney's 2011 Femme Fatale tour ... an estimated $500k.
Britney and Rosengart say Jamie is ill-equipped to manage Britney's business affairs, saying his family "struggled financially under his leadership and filed for bankruptcy in 1998."
The docs claim Britney's life has been upended by the conflict she has with her dad. The docs say they don't speak and the current situation is "traumatizing, insane and depressing."
The docs call the relationship "venomous" and "it impairs Ms. Spears's mental health, her well-being, and her ability to pursue and continue with her extraordinary career."
One of the more interesting parts of the document is the intimation Britney may have possibly needed some sort of conservatorship 13 years ago but things have drastically changed ... "Since receiving professional medical care at the outset of this conservatorship over thirteen years ago, Ms. Spears is clearly in a different place now, and she has been for many years. The entire world has witnessed Ms. Spears working tirelessly -- with astonishing dedication, precision, and excellence -- as a musical artist and performer, an exceptional earner for Mr. Spears (and others) who had a financial interest in making sure she would continue to work and perform."
The docs quote Forbes as saying given what Britney has earned, her net worth is "shockingly low," and Britney and Rosengart appear to be placing a big part of the blame on Jamie.