Mathew Rosengart, Hollywood’s King of Litigators, Talks Britney Spears Conservatorship, Early Legal Influences and Standing Up Against Bullies

Mathew Rosengart arrives on the rooftop restaurant of the Waldorf Astoria Beverly Hills wearing a wheaten wool coat from Barney’s, steeled against the early February cold snap that has whipped across Los Angeles. The sky is awash in Monet watercolors, the twinkling lights of Beverly Hills are aglitter. “It’s imperfect, and the clichés are often true, but there is something magical about L.A. at night,” says Rosengart, his eyes locked on the scenic stretch of palm trees and swimming pools below.

It’s nearing 6 p.m. and Rosengart, Variety’s 2022 Power of Law honoree, has walked to the hotel from the nearby Century City offices of Greenberg Traurig, where he has been a litigation partner since joining the prestigious international firm in 2011.

A former federal prosecutor with the United States Justice Dept. who cut his teeth clerking for Supreme Court Justice David Souter, Rosengart’s reputation as a Hollywood power attorney has long been established. A governor of the Beverly Hills Bar Assn., the formidable litigator represents a roster of high-price-tag clients, from Verizon and Steven Spielberg to Eddie Vedder, Casey Affleck and two-time Oscar-winner and Community Organized Relief Effort (CORE) co-founder Sean Penn, who Rosengart readily refers to as “an uber-mensch.”

Rosengart represented Penn in a victorious 2015 $10 million defamation suit against “Empire” creator Lee Daniels, and handles a myriad of other legal matters for the esteemed multihyphenate. The Penn-Rosengart partnership extends also to poolside dinner parties. Penn is a “regular” at the Rosengart household where the attorney’s grilled Rib Eye steak is a “centerpiece” on the menu. Rosengart cooks it “rare.”

“Matt is a lawyer who gives lawyers a good name,” says Penn. “I always feel that his commitment to the law is equaled only to his commitment to friends, family and clients. That said, his wizardly grill-master skills threaten to embody an even higher integrity.”

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Mathew Rosengart, a shareholder at Greenberg Traurig, joined the prestigious worldwide firm in 2011. Adam Amengual for Variety

Rosengart’s accolades are copious. A steady fixture in publications ranging from the National Law Journal to the American Lawyer, in March, Rosengart was named a 2022 California Lawyer Attorney of the Year by the Los Angeles and San Francisco Daily Journal. Most important, his courtroom record is unassailable.

Rosengart has not lost a single trial.

Those decades of diligence, perseverance and dedication are what primed the legal counsel for his latest professional chapter, the one in which he rocketed to fame in November 2021 for emancipating pop star Britney Spears from her 13-year, court-mandated conservatorship.

The day we meet, Spears has posted a note of gratitude to Rosengart on her Instagram page under a photo of them in “accidentally” matching outfits — Rosengart in a pink, gingham-plaid button-down; Spears in a blush pink dress. Rosengart has “turned [her] life around,” writes Spears, peppering the post with a string of red rose emojis.

“He’s not like a regular lawyer. He’s a cool lawyer,” one Spears follower posts.

Rosengart’s phone has not stopped ringing.

“It’s been a lot,” says Rosengart, running a hand through his thick brown hair. At 59 years old, there’s a lot of it, swept back like a small crested wave — it’s New England prep school hair. In sharp contrast to the groupies in pink Britney wigs and “Toxic” concert tees circling him on the courthouse steps, Rosengart evokes a character from a Salinger novella.

The past half-year has proven a whirlwind for Rosengart, who will be feted at Variety’s Power of Law breakfast on April 20 at the Four Seasons Los Angeles at Beverly Hills. Penn will deliver introductory remarks.

If accepting Spears’ case in July 2021 was the prologue to Rosengart’s celebrity, the result — the pop star’s freedom — has elevated Rosengart to an even higher stratosphere of fame. Throughout Spears’ trial, throngs of #FreeBritney protestors outside L.A.’s Stanley Mosk Courthouse brandished signs hailing Rosengart a hero, christening him with pet monikers such as “Zaddy” and “Rosengod.”

A flurry of memes — one comparing Rosengart to Superman — and stan accounts have stormed social media; a Twitter account dubbed “Mathew Rosengart’s investigation assistant” has amassed 16,500,000 followers. Courtney Love fashioned a viral meme declaring Rosengart “America’s Boyfriend.” Another meme brands the litigator “King Rosengart.” In a “Late Night With Seth Meyers” segment that aired last August, staff writer Dina Gusovsky bemoans the fact that Spears “found a nice Jewish lawyer” while she’s still single. And in one video mash-up, courtroom sketches and superimposed hearts are intercut with a clip of Rosengart driving his Porsche Panamera amidst the thumping backdrop of rapper Saweetie’s “My Type.”

“I’m still processing a lot of it,” Rosengart admits of the roaring media maelstrom.

Michael Mann, four-time Oscar-nominated filmmaker (“The Insider,” “The Aviator”) and Rosengart’s longtime client and friend, describes the courtroom heavyweight as “intellectually curious.”

“There are certain things worth fighting for, and I believe Matt knows that,” says Mann. “He has a very clear sense of right versus wrong.”

Per Mann, Rosengart affectionately dubs the “Heat” filmmaker his “consigliere.”

“On top of everything, Matt is also just a very, very lovely guy,” says Mann. “And if you were to ask me what Matt’s real strength is — I think it’s his creativity. And it’s this creativity that enables Matt to implement innovative approaches to whatever case that he decides to take on.”

But while the apotheosis of Rosengart as a courtroom pin-up — a de facto Cary Grant of the California (and New York) bar — is the dizzying byproduct of rescuing a pop princess from veritable imprisonment, the conservatorship case of Spears does not, Rosengart is quick to remind, fall under the purview of “entertainment law.” Rather, it is a legal case predicated on civics, civil liberties and government intervention. It is a case about one’s Constitutional right to choose one’s attorney, a case about principles. It is also — and glaringly so — a case about “bullying.”

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In November 2021, a zealous scrum of Britney Spears fans mobbed Rosengart outside the Stanley Mosk Courthouse in downtown Los Angeles. AP

“Listening to Britney’s own June 23 court testimony, which was before I was involved or retained, I heard the voice of a woman who had been bullied,” explains Rosengart of his decision to rep Spears. By trade, Rosengart is not a probate attorney; by the time he walked into that courthouse on July 14, 2021, he was a preeminent expert in conservatorship law.

“I’ve always hated bullies and bullying, even in high school when I saw some of my classmates being bullied and I helped them,” Rosengart continues. “Obviously, bullying a woman is even more detestable and abhorrent. I heard that in Britney’s own June 23 testimony, which was a few weeks before I became involved, and it disturbed me greatly, but also compelled me, both as a lawyer and person, to want to help, and I believed I could.”

Rosengart is fiercely protective of all his clients, but of Spears, whose every move is tracked like an animal tagged for study, he is especially so. There is a great honor that comes with representing a global juggernaut, but there is also an extraordinary weight. Rosengart’s ethics are demonstrably ironclad. Save for a guest DJ spot on E Street Radio in which he dedicated “No Surrender” to Spears — “I couldn’t say no,” says Rosengart, a lifelong, dyed-in-the-wool Bruce Springsteen fanatic — there is not much he will reveal publicly about the pop icon.

But renown has never been Rosengart’s impetus for any case he’s taken on. In getting to know Rosengart, one gets the feeling his greatest worry is, in fact, not doing enough to save the world, not doing enough to protect his clients, even when he has completely, as Spears wrote, turned their lives around for the better. Aside from the occasional golf game — “I try to play as much as I can” — and an annual vacation to Hawaii, Rosengart works nonstop. The pursuit of justice is Rosengart’s primary drive. And when it came to Spears, there were a host of human rights queries Rosengart could not ignore.

“I was concerned that she had been deprived of certain civil or fundamental liberties, even as she was earning hundreds of millions of dollars as a performer, from which others were benefitting,” he says. “As a federal prosecutor, I had dealt with criminals charged with serious felonies, all of whom had the right to hire their own private attorney, to fiercely advocate for them, to fight for them.”

Further, Rosengart wonders, “Why had Britney been deprived of that basic right for 13 years? Other troubling, but compelling questions included: why was a 39-year-old woman still in a controlling conservatorship, after more than a decade? Were there conflicts of interest? Were there less restrictive alternatives? Was there an exit strategy, consistent with the goals of a conservatorship or was it being perpetuated for reasons that were inconsistent with Britney’s stated desires and rights as a human? Was the fact that Britney was a woman relevant to the situation she was in? Would this have happened to a man?”

Like many an idealistic teen, Rosengart’s passion for justice is, at least in part, rooted in “To Kill a Mockingbird.” He was about 16 years old and a high school student on Long Island when he read Harper Lee’s Pulitzer Prize-winning classic about racial injustice in 1930s Alabama. Atticus Finch, the novel’s attorney protagonist and an emblem of moral heroism, awoke in Rosengart a fiery ache.

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In a letter penned on Rosengart’s behalf, Justice David Souter described his former law clerk as “a man of solid personal integrity.” Courtesy of Mathew Rosengart

“I knew then I wanted to go work for the Justice Department and fight for justice,” he says.

But it was athletics that occupied the bulk of Rosengart’s adolescence in Lido Beach, New York. “Growing up, I was a jock and a sports junkie,” he says. Team pennants lined his bedroom wall: Yankees, New York Giants, Rangers, Knicks.

“I had all of them, and we built it up like it was a gift,” says Rosengart. “My parents would bring a pennant home when they went to Madison Square Garden. And then another one. After several years, I had the full NBA roster.” In contrast, Rosengart’s older brother, Todd, decorated his room with shelf models of human organs — the brain, liver, lungs. At age 23, after completing an accelerated five-year med school program at Northwestern, Todd would become a cardiothoracic surgeon, prompting Rosengart to quip, “I am the black sheep of the family.”

It was an “idyllic” childhood, but one also marred by tragedy. Rosengart was 13 when his father, an OBGYN, the beloved “town doctor” who delivered all the local babies, died at age 46 of a heart attack. His mother later remarried, but his father’s death was a “crushing blow.”

“I’m probably still grappling with it in ways that I haven’t come to terms with yet,” he admits.

After graduating from high school at 17, Rosengart was accepted early decision to Tulane U., graduating with a B.A. in social science. In 1987, Rosengart graduated cum laude from Boston College Law School. His commitment to the arena of justice fully abloom, Rosengart next secured a coveted clerkship with Justice Souter in the New Hampshire Supreme Court, an experience that would forever shape the trajectory of Rosengart’s professional sojourn.

“He is the formative mentor of my career,” says Rosengart. “He is not just a father figure — he is a founding father figure.”

Souter, appointed to the United States Supreme Court by President George H. W. Bush in 1990, is, per Rosengart, “the type of justice that doesn’t exist anymore.”

“The justice is a true judicial conservative, meaning he respects stare decisis —precedent — and did not let politics or personal views get in the way, at all. The best evidence of this is that, very early in his tenure on the Supreme Court, he was essentially responsible for upholding Roe v. Wade. I’ve never met a man more comfortable in his skin or with more equanimity, putting aside his utter brilliance. He is the type of liberal Republican that is basically now extinct.”

Rosengart could — and does — gush about Souter for hours. Souter is a centrifugal intellectual force in Rosengart’s career, a proverbial north star, the person to whom Rosengart turns when grappling with legal questions and quandaries about life. It is Souter who solidified Rosengart’s decision to become a litigator. It is Souter with whom Rosengart often discussed the judicial philosophies inherent within Learned Hand’s 1944 “Spirit of Liberty” speech, the conviction that true, pure freedom is when one “is not too sure what is right.” One primary takeaway: “When formulating a legal position or theory of the case, be cognizant of the other side’s position and weaknesses in your own case,” says Rosengart.

It is Souter whose advice Rosengart sought when invited to speak as a distinguished guest lecturer at both Harvard Law School and B.C. Law School this past February. (Ultimately, Rosengart wove lyrics from Springsteen’s “Reason to Believe” through his speech, citing the need for optimism even in the midst of dark and challenging times.)

Every summer — “the pandemic was one of the only years we’ve missed” — Rosengart and Souter gather for a reunion. Souter makes his home an hour south of New Hampshire’s White Mountains, and each year they “choose a different mountain to hike.” They drive to Boston, drink two gin and tonics apiece at the Ritz Carlton — “always two, not one, not three, [it’s] tradition” — then stroll across the Boston Common past the Massachusetts State House where they stand and admire Augustus Saint-Gaudens’ bronze sculpture memorial to Robert Gould Shaw and the Massachusetts 54th Regiment. Before it shuttered, they dined at Locke-Ober, the city’s fourth oldest restaurant and a venerable mainstay of Boston Brahmin society.

“Being able to sustain that relationship for more than 30 years is one of the most rewarding parts of my personal and professional life,” says Rosengart of his enduring friendship with Souter, who taught Rosengart so much of what it means not only to be an attorney, but to be of public service and contribute to the greater good of American society.

“Justice Souter taught me, and I’m not saying I have achieved this, but he taught me that to be a really great lawyer — not a good lawyer — but a great lawyer, in addition to the more obvious components of passion, striving for excellence and knowing every fact of your case, you need to have humility. Relatedly, my mentor at the Justice Department, a legendary lawyer, told me that three critical traits you need to succeed as a federal prosecutor are thoughtfulness, hard work, and decency. The latter because you have tremendous power, at a very young age, to drastically affect someone’s life by charging them with a federal crime, which is reputationally irreversible for that person.”

Rosengart carried those core principles throughout his 10-year tenure working for the Dept. of Justice. In the beginning, Rosengart tried every case he could: “I just wanted to be on my feet in front of a jury. It was exhilarating and the best way to get invaluable experience at a really young age.”

Rosengart handled “about nine jury trials” that first year as an assistant U.S. attorney. His inaugural case played out in a Jacksonville, Fla., courtroom, and centered on Lakeisha Brisbane, a woman accused of forging treasury checks. She was Rosengart’s first criminal defendant, and he has never forgotten her.

“As low profile as it was, it was a challenging case, which lacked jury appeal,” Rosengart recalls. “As fortunate as I’ve been with varied high-profile cases and trials, you never forget your first trial. I got to stand up in court and tell the jury, ‘My name is Mathew Rosengart and I represent the United States of America.’ I’ll never forget that pride I felt as a young litigator.”

In the case United States v. Henry Cisneros, which commenced in 1995, Rosengart examined former Secretary of State Warren Christopher, as well as United States senators, the White House counsel, and Leon Panetta, former Chief of Staff to President Bill Clinton. In 2000, Rosengart worked on the United States v. James Riady case in which Riady, an Indonesian billionaire, was convicted for illegal contributions to President Clinton’s 1996 presidential campaign. Riady had befriended Clinton in Little Rock, Ark., when the future president was just starting out as a young politician.

“Some of the FBI agents on the case had a theory that Clinton was the Manchurian candidate,” says Rosengart, who obtained a felony conviction against Riady to the tune of a $8.6 million fine, which, at the time, was the largest campaign finance fine in history.

But Rosengart’s proudest moment as a young gun attorney was disobeying the orders of his then-supervisor, who urged Rosengart to seek a life sentence against a young Black man, nicknamed “Eager Beagle,” convicted for dealing crack cocaine. He was “a lower-level mule, not a kingpin,” but the mid-1990s case was unfolding at the height of the war on drugs movement and all of its peripheral hysteria, and this was the defendant’s third felony conviction. Rosengart stood his ground, deeming the defendant “more sad than bad” and not the category of criminal for whom lifetime imprisonment was just punishment.

Rosengart refused to file documents seeking a life sentence.

“I knew it was the right thing to do, consistent with the Justice Dept.’s mission statement of ‘doing justice,’ doing the right thing no matter the ramifications, which is a maxim I’ve tried to follow throughout my career.”

In 2008, several years after transitioning to private practice, Rosengart took on the case signaling his entrée into the arena of the entertainment biz, winning a $8 million “cutting rights” case for Oscar-winning filmmaker Kenneth Lonergan regarding his film “Margaret.”

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After an “epic six-year battle” over Kenneth Lonergan’s “Margaret,” Mathew Rosengart and the filmmaker celebrate a massive lawsuit win in the War Room of Rosengart’s office. Courtesy of Mathew Rosengart

“Matt was just amazing. He was like a one-man band,” says Lonergan of the tempestuous six-year case, in which film financier Gary Gilbert sued to seize creative control of the New York-set drama (starring Matt Damon and Anna Paquin) and shave its running time down to two hours. In the end, after a parade of luminaries including Damon, co-star Mark Ruffalo and Martin Scorsese threatened to take the stand, and on the heels of Rosengart cross-examining him, Gilbert filed for a dismissal of the case. In 2011, the theatrical version of “Margaret” was released at a running time of two hours and 30 minutes; Lonergan’s cut is longer.

“He was really devoted, dedicated, hard-working,” Lonergan continues. “He was a relentless litigator. I told him that he should create a new description for what he does, because he was both a lawyer and a publicist and an agent — and just an all-around advocate. He did much, much more than you could expect anyone to do. He gave the film life by getting it written about a lot, all in service of the lawsuit. He gets very personally invested in his cases. It was an amazing thing to watch him in the arbitration. It was like watching Muhammad Ali pick apart an opponent round after round after round — until there was nothing left.”

In the aftermath of the Britney Spears conservatorship case, and as he prepares to return to court on July 27 to address additional financial matters in the case, Rosengart has spent ample time considering what enduring mark the pop star’s legal victory might have on the American legal system. “Britney’s bravery and perseverance were crucial and she, of course, gets the credit,” says Rosengart. He’s hopeful the case’s landmark outcome will expand far beyond the parameters of Spears’ incandescent fame.

“We’re living in very polarizing times but these are [conservatorship law] issues that the United States Congress, Gov. Newsom and the California legislature are examining on a bipartisan basis as a result of the case and the spotlight that Britney shined on her own conservatorship and therefore others throughout the country,” says Rosengart. “Several congressmen have been in touch and, on the Senate side, support has ranged from Sen. Richard Blumenthal on the left to Sen. Ted Cruz on the right, which is remarkable.”

What’s been most meaningful to Rosengart throughout this heady, extraordinary experience is the unflagging support of his dear friend Souter. Souter, who does not watch TV and until recently didn’t even know who Spears was, has continually reminded Rosengart that the press is not what matters. What matters is justice.

“A New Hampshire congressman from back in the days of my professional youth would have congratulated you on the ‘good ink’ you have gotten after your victories in the Spears case,” penned Souter in a letter to Rosengart in December. “Those are my words too after having the fun of reading your coverage. But there’s much more than fun conveyed by those press reports and that’s the sense of your professionalism. That’s why I am proud of you, and believe me, I am very proud of you.”

As for what comes next, Rosengart is attempting, while it may sometimes be difficult, to linger and relish in being in the present.

“I am focused on my cases and representing my clients — zealously and vigorously,” he says. “And that’s something I expressed to the students at Harvard when I recently spoke there: don’t over-plan. Some of the successes I’ve had are attributable in part to good luck, or fate. Being in the right place at the right time, but being prepared. John Lennon famously said ‘life is what happens while you’re busy making other plans.’ That’s something I think about, even if I don’t always adhere to it.”