Britney Spears' Attorney Speaks Out After Her Conservatorship Is Terminated: 'Monumental Day'

Mathew Rosengart, the attorney who has been representing Britney Spears in her fight to end her conservatorship, is speaking out after his client's "monumental" victory in court.

Spears, 39, had her conservatorship terminated after 13 years in a court hearing on Friday, and in a statement to reporters gathered outside the courthouse afterwards, Rosengart called it a "monumental day" for the pop star.

"What's next for Britney is up to one person — and this is the first time we can say this in a decade. It's up to Britney," he said. "Britney, as of today, is a free woman."

"I thank her for her courage and poise and power and for our relationship," he added.

Although Rosengart spoke in harsh terms about the Spears family, including Britney's father Jamie, who was suspended as her estate conservator in September, he told reporters that it was "up to my client Britney" whether there would be a lawsuit.

Rosengart, who has represented Spears since July, first filed court documents to move forward in asking Judge Brenda Penny to end the pop star's conservatorship in September, weeks after Spears' father and then-estate conservator Jamie did the same.

In the filing, Rosengart claimed that Britney's conservatorship no longer served a purpose and needed to be terminated immediately, which echoed Jamie's filing.

"[Jamie's] suspension was (and is) a necessary first—and substantial— step toward Ms. Spears' freedom and ending the Kafkaesque nightmare imposed upon her by her father, so that her dignity and basic liberties can be restored," the document read, later adding, "Britney Spears' life matters. Britney Spears' well-being matters. And under the circumstances, every day matters because every day Mr. Spears clings to his post is another day of anguish and harm to his daughter, which is avoidable via immediate suspension."

After Jamie was officially suspended on Sept. 29, Spears thanked Rosengart on Instagram, writing: "Thankfully I found an amazing attorney Mathew Rosengart who has helped change my life!!!!"

Weeks later, Rosengart filed additional court documents accusing Jamie of having ulterior motives after he unexpectedly reversed his stance in September on the necessity of Britney's conservatorship.

He filed a request on Oct. 1 to have Jamie deposed, and questioned in court documents whether Jamie was "motivated by a desire to bolster his reputation or to avoid his deposition or responding to the outstanding discovery served on him in August."

Jamie's lawyer did not immediately respond to PEOPLE's request for comment.

"After more than a decade, the time has come for Ms. Spears's freedom," Rosengart said in the documents. "Ms. Spears has made her wishes known about ending the conservatorship she has endured for so long and she has pleaded with this Court to 'let her have her life back,' without an evaluation, recently attending two Court hearings and asking this Court directly to end the conservatorship. It is respectfully submitted — with the consent of all parties — that the time has come."

For his part, Jamie has defended his role as the conservator of Britney's estate and has insisted that he only ever had his daughter's best interest at heart.

"Mr. Spears loves his daughter Britney unconditionally. For 13 years, he has tried to do what is in her best interests, whether as a conservator or her father," read a statement released by his former lawyer Vivian Thoreen on Sept. 30.