In the years since a judge gave the father of Britney Spears broad control over her life and finances, concerned fans have questioned how the court could continue to deem her unable to protect and care for herself despite the fact that she was still a performing pop star.

Her father and others involved in the conservatorship maintained that it was a smooth-running machine that had rescued her from a low point and benefited Ms. Spears, and that she could move to end it whenever she wanted.

All the while, she stayed largely silent on the subject in public.

But now, confidential court records obtained by The New York Times reveal that Ms. Spears, 39, expressed serious opposition to the conservatorship earlier and more often than had previously been known, and said that it restricted everything from whom she dated to the color of her kitchen cabinets.

“She articulated she feels the conservatorship has become an oppressive and controlling tool against her,” a court investigator assigned to her case wrote in a 2016 report. The system had “too much control,” Ms. Spears said, according to the investigator’s account of the conversation. “Too, too much!”

Ms. Spears informed the investigator that she wanted the conservatorship terminated as soon as possible. “She is ‘sick of being taken advantage of’ and she said she is the one working and earning her money but everyone around her is on her payroll,” the investigator wrote.

In 2019, Ms. Spears told the court that she had felt forced by the conservatorship into a stay at a mental health facility and to perform against her will.

At the helm of the singer’s life and finances for most of that time was her once-estranged father, James P. Spears. Mr. Spears, known as Jamie, was appointed conservator in 2008, shortly after Ms. Spears was placed in two involuntary psychiatric holds amid a series of public struggles and concerns around her mental health and substance abuse.

The newly obtained court records show that Ms. Spears has called into question his fitness for the role. As early as 2014, in a hearing closed to the public, Ms. Spears’s court-appointed lawyer, Samuel D. Ingham III, said his client wanted to explore the removal of her father as conservator, citing his drinking, among other objections she had raised in what he called a “shopping list” of grievances.

Last year, Mr. Ingham brought these issues to the fore, telling the judge that Ms. Spears was “afraid of her father,” who remains a steward of her nearly $60 million fortune.

On Wednesday, Ms. Spears is scheduled to address the Los Angeles court directly — a rare move she requested on an expedited basis. It is unclear whether her remarks will be made in public, but her relationship with her father is expected to be a central topic.

Representatives for Mr. Spears, 68, declined to comment, citing the pending court hearing. But they have previously said the conservatorship was necessary to protect Ms. Spears from exploitation and harm and that Mr. Spears has been a dutiful father, acting out of love for his daughter.

“Any time Britney wants to end her conservatorship, she can ask her lawyer to file a petition to terminate it; she has always had this right but in 13 years has never exercised it,” Vivian Lee Thoreen, a lawyer for Mr. Spears, said in a statement to People earlier this year. “Britney knows that her Daddy loves her, and that he will be there for her whenever and if she needs him, just as he always has been — conservatorship or not.”

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Theirs has long been a difficult and dysfunctional relationship, according to the court records and interviews with many people who know the family. But that dynamic grew even more complicated after Mr. Spears — a recovering alcoholic who has faced accusations of physical and verbal abuse — took the lead in wrestling what he saw as his adult daughter’s demons.

Ms. Spears said her father was “obsessed” with her in the sense that he wanted to control everything about her, according to the investigator’s report. She could not make friends without his approval.

Even as she earned millions from a successful Las Vegas residency, she said she was limited to a $2,000 weekly allowance, according to the records.

Any mistakes resulted in “very harsh” consequences, Ms. Spears added, according to the report. The conservatorship “comes with a lot of fear,” she said.

After consulting with Ms. Spears, her conservators and her doctors, the probate investigator concluded in 2016 that the conservatorship remained in Ms. Spears’s best interests based on her complex finances, susceptibility to undue influence and “intermittent” drug issues, though the report called for “a pathway to independence and the eventual termination of the conservatorship.”

The records provide only an incomplete snapshot of Ms. Spears’s sentiments and situation throughout a 13-year saga. Still, they present in great detail her discontent with the arrangement, in particular her concerns that her views about her father and his own behaviors were not being appropriately considered.

Experts say conservatorships should prioritize the wishes of the conservatee and help them regain their independence. The arrangements are supposed to be a last resort for people who cannot take care of their basic needs, such as those with significant disabilities or older people with dementia, yet Ms. Spears has been able to perform and profit for more than a decade.

Jamie and Britney

What the court records make clear is that the battle over the conservatorship is rooted in the family’s troubled history.

Debbie Sanders Cross, Mr. Spears’s first wife, who remains his friend, said his own “very difficult upbringing” had influenced his perspective. “I really think that’s why he’s trying to be so protective of Britney,” she said.

Mr. Spears had spent much of his life in Kentwood, a tiny Louisiana town where he was a star quarterback. His father, a boilermaker, was strict and demanding. “His daddy was so hard on him, but Jamie loved him and respected him,” Mr. Spears’s former football coach, Elton Shaw, recalled.

Mr. Spears’s youth was marked by tragedy: His mother died by suicide on the grave of her infant son when Mr. Spears was 13, according to the local paper. Mr. Spears survived a car accident that killed a football teammate four years later. At 22, he was arrested on drug and driving while intoxicated charges, according to a news report.

When Lynne Spears, his second wife and Britney’s mother, filed for divorce in 1980, she requested a temporary restraining order, citing a fear that he would “become angry when he is served with these papers” and harass or harm her, “especially if he has been drinking alcoholic beverages, as he has done in the past.”

The couple reconciled, but Mr. Spears’s instability haunted Ms. Spears’s childhood, the family has said. In her 2008 memoir, Lynne recalled years of “verbal abuse, abandonment” and “erratic behavior.”

The family struggled financially, and in 1998, just months before the release of Ms. Spears’s blockbuster first album, the Spearses filed for bankruptcy. The couple divorced in 2002. Ms. Spears said later that it was the “best thing that ever happened to our family.”

Mr. Spears was present only intermittently during his daughter’s rise to pop stardom. In 2004, according to a court filing, Mr. Spears went to rehab for alcoholism at the urging of his daughter.

But by 2007, Ms. Spears was struggling herself. Humiliation by the press, stalking by the paparazzi, speculation around her mental health and substance abuse and a custody battle over her two young sons helped lead Ms. Spears to a breaking point.

Mr. Spears reappeared for what he and his ex-wife, Lynne, viewed as an urgent rescue mission.

Along with his business manager, Louise M. Taylor, he prayed and fasted before he petitioned a judge for a temporary conservatorship of Ms. Spears, Lynne wrote in her memoir. Ms. Taylor later became a business manager of Ms. Spears’s estate and an architect of her comeback.

The singer stressed that she did not want her father in charge, a lawyer she consulted at the time has said. But the judge overseeing the case, Reva Goetz, deemed Ms. Spears incapable of hiring her own counsel and appointed Mr. Ingham, the lawyer who represents her to this day.

In February 2008, according to court records, Judge Goetz deemed Mr. Spears “a suitable and qualified person” and granted him broad control over his daughter’s daily life and, alongside a co-conservator, her finances.

“Everything he does, he feels is in the best interest of his daughters and his family,” said Mitch Covington, a friend of Mr. Spears’s.

Ms. Spears quickly went back to work. Within a year of being deemed unable to care for herself, she guest-starred on national television, released a No. 1 album and was preparing to embark on a run of almost 100 shows around the world.

Aside from his salary as conservator — now about $16,000 per month, plus $2,000 a month for office space rent — Mr. Spears was approved by the court to receive a percentage of various deals signed for his daughter.

In 2011, he received a 2.95 percent commission for his work on Ms. Spears’s successful Femme Fatale tour. And in 2014, he was granted 1.5 percent of gross revenues from the performances and merchandising tied to her Las Vegas residency, “Piece of Me,” which went on to earn a reported $138 million across nearly 250 shows.

The dual role of looking out for Ms. Spears’s best interests as conservator and reaping more profits each time she performed was “fraught with conflict,” according to W. Michael Hensley, a probate lawyer in California who works as a fee examination expert and is not involved in the Spears case.

Questioning her father’s role

Court records reveal Ms. Spears’s concerns that her father was hardly the person to be setting, and enforcing, the rules that governed her life.

Ms. Spears’s first tour under the conservatorship, The Circus Starring Britney Spears, was designed to be a dry one, with cast and crew forbidden from drinking alcohol — or even energy drinks — around Ms. Spears, according to three people who worked on it.

During this period, a former nanny and housekeeper for Ms. Spears claimed Mr. Spears engaged in “verbal abuse, tirades, inappropriate behavior and alcoholic relapses,” according to a legal letter sent in 2010 that threatened a lawsuit.

In 2014, Mr. Ingham told the court that Ms. Spears believed her father was drinking, according to a transcript of the closed hearing. Lawyers representing the conservatorship responded that Mr. Spears had voluntarily submitted to regularly scheduled alcohol tests and never failed. Mr. Spears’s lawyer said he took one random test, but refused to take any more, calling the request inappropriate.

“Absolutely inappropriate,” the judge replied. “And who is she to be demanding that of anybody?”

Mr. Ingham told the court that his client was upset that it was not taking her concerns seriously. “She said to me, when she gave me this shopping list, that she anticipates that, as it has been done before, the court will simply sweep it under the carpet and ignore any negative inferences with regard to Mr. Spears,” Mr. Ingham said, according to a transcript.

Mr. Ingham also raised Ms. Spears’s urgent desire to terminate the conservatorship altogether. She had even mentioned the possibility of changing her lifestyle and retiring, but believed the conservatorship precluded that, he said, according to a transcript.

In response to Ms. Spears’s request to end the arrangement, the judge said that if she established a healthy relationship with a therapist and returned one year’s worth of clean drug tests, she would take the matter under consideration. But she would not guarantee it.

Those gathered, including the judge and lawyers on both sides, raised the possibility that Ms. Spears’s boyfriend was provoking her discontent.

Behind closed doors

In 2016, Ms. Spears released her ninth studio album and performed more than 50 times in Las Vegas. But in private, she was again protesting the conservatorship, according to a report written by a probate investigator. (In California conservatorships, a court investigator is tasked with conducting periodic reviews for the judge.)

Ms. Spears told the investigator that she was “very angry” about the way her life was being run, and described security around her at all times. She was also being tested for drugs numerous times weekly, and her credit card was held by her security team or assistant and used at their discretion, the report said.

Ms. Spears wanted to add feminine touches to her home, like restaining her kitchen cabinets, she told the investigator, but was forbidden by her father, who told her too much money was being spent.

The public image of Ms. Spears’s life gave little sense of the turmoil she was expressing privately. An Instagram feed presented her as playfully approachable, and a new, lucrative Las Vegas show was set to begin in February 2019.

Then, a month before the opening, Ms. Spears announced an “indefinite work hiatus,” canceling the residency. Mr. Spears had “almost died” after suffering a ruptured colon, according to a statement, which noted the pair’s “very special relationship.”

That spring, Ms. Spears appeared at a closed-door hearing and read a statement. According to a transcript, she asserted that she had been forced into a mental health facility against her will on exaggerated grounds, which she viewed as punishment for standing up for herself and making an objection during a rehearsal.

She also claimed she had been forced to perform while sick with a 104-degree fever, calling it one of the scariest moments of her life.

Ms. Spears ran down a list of her recent accomplishments, including tours and album releases. She told those present there was nothing wrong with her.

A transcript of the hearing was mistakenly unsealed, and portions were first reported by TMZ.

That summer brought further tumult. In August, there was an alleged physical altercation between Mr. Spears and Ms. Spears’s 13-year-old son. No charges were filed in the incident, but the child’s father, Kevin Federline, was granted a restraining order barring Mr. Spears from seeing the children.

Two weeks later, Mr. Spears, citing health problems, temporarily stepped down from his position as conservator of Ms. Spears’s person and was replaced by a licensed professional. He remained in control of Ms. Spears’s money.

By September 2020, a flurry of courtroom activity indicated publicly that something had shifted. Mr. Ingham filed court papers saying that Ms. Spears “is vehemently opposed to this effort by her father to keep her legal struggle hidden away in the closet as a family secret.”

Mr. Ingham then filed complaints about the ways Mr. Spears managed the singer’s money, asserting that he paid excessive fees of over $300,000 to the firm of her then-business manager, Ms. Taylor. (In court, a lawyer for Mr. Spears called the fees reasonable.)

As the fight drags on, the bills are piling up — and, in a quirk of the conservatorship system, Ms. Spears has to pay for lawyers on both sides, including those arguing against her wishes in court. A recent $890,000 bill from one set of Mr. Spears’s lawyers, covering about four months of work, included media strategizing for defending the conservatorship.

At a public court hearing in November, Ms. Spears’s mother moved to support the removal of Mr. Spears as conservator. Through a lawyer, she called the father-daughter relationship “toxic” and said it was “time to start fresh,” adding that Mr. Spears had referred to his daughter as “a racehorse who has to be handled like one.”

That day, Judge Brenda Penny, who had replaced Judge Goetz on the case, declined a request from Mr. Ingham to suspend Mr. Spears immediately, but left the door open to consider removing him in the future. Judge Penny approved a wealth management firm to serve as co-conservator of the estate alongside Mr. Spears.

Mr. Ingham has not filed a petition to remove Mr. Spears permanently.

Mr. Spears has recently been back home in Kentwood, where he is known to host crawfish boils and stop by the town’s VFW bar. But he mostly keeps to himself. “He is just the same old Jamie,” his former football coach, Mr. Shaw, said.

Mr. Spears recently sold the house Ms. Spears grew up in. He has been staying down a winding country road on the outskirts of town, in an RV parked at a warehouse that has stored the boxed-up relics of his daughter’s megawatt career.

Alain Delaquérière contributed research. Lauren Herstik contributed reporting from Los Angeles.