When Jonny King was 10 years old, his parents took him on a jazz cruise to the Bahamas, with trumpeter Dizzy Gillespie headlining. It was 1975.

Ed and Ruth King preferred classical symphonies. But they were struck by their son's early tilt toward jazz and his ability to plunk out songs by ear on the piano, or make them up on the spot.

Having hung out at clubs around New York (his mom befriended a lot of bartenders and managers to get him in), he met greats like Oscar Peterson and Cannonball Adderley, announcing himself as a jazz pianist. But even Ruth King was surprised when, during one evening's show aboard ship, Jonny King rushed the stage in response to Gillespie's call-out for audience members to join in a jam. “I tried grabbing his sleeve but there was no keeping him from the bandstand,” she remembers.

“I played some boogie-woogie and a 10-year-old's idea of bebop—whatever it was, I seemed to kill it,” King recalled recently. “The rest of the trip people were asking for my autograph, and I got to pal around with Dizzy and the band. I pretty much knew at that point I was meant to be a jazz musician.”

Four decades later, King has more than delivered on that promise. Sitting in with heavyweight drummer Art Blakey while in his teens, and later owning a slot at storied jazz bar Bradley's in Greenwich Village, King went on to play with the leading Young Turks of his era. That includes saxophonists Joshua Redman, Kenny Garrett and Joe Lovano, trumpeters Randy Brecker and Roy Hargrove, vibraphonists Joe Locke and Steve Nelson, guitarist Freddie Green, bassist Christian McBride and drummers Billy Drummond and Peter Washington. Reviewing an early CD, Downbeat magazine called King “one of the strongest piano voices of a new generation and a bandleader who kicks ass.”

King also became a prolific composer, despite limited formal training and poor sight-reading skills. Alto saxophonist Steve Wilson, recently touring worldwide with pianist Chick Corea, says, “I could record an entire album of Jonny's songs—make that a double album—and be happy. All his tunes are hip and well thought out, they're challenging and playable and full of surprises, rhythmically and harmonically. It's amazing what he doesn't know, because he knows so much.”

But for all the success there are noticeable gaps in King's output. His website lists sporadic performance dates, with months falling between gigs and rarely beyond smaller New York venues like Small's and Mezzrow in Greenwich Village. And he's recorded only four albums as a leader, the last in 2012, leaving an extensive original songbook uncaptured. As Wilson, who appeared on King's 1997 CD The Meltdown, puts it: “Even after all these years of playing at a high level, Jonny may be the best-kept jazz secret in New York—not among fellow musicians, but among the listening public.”

King is well aware of his lower profile. “Some people think I was sick or they come up after a set and ask, how come we never heard of you before?” he says. In fact, it's remarkable he can sustain any musical career given that he leads a double, unmusical life—as a trademark and copyright litigator for one of the country's top intellectual property law firms.

While most of his peers are touring, rehearsing, recording or teaching, King—whose day-job name is Jonathan Z. King—is prepping witnesses for deposition, reviewing expert reports and arguing in court or before the Trademark Trial and Appeal Board on behalf of major drug companies, brand-name apparel firms and music conglomerates. He's notched landmark wins, including cases involving trademarking internet search terms and copyrighting the resale of digital files.

As if his trial practice isn't consuming enough, in 2013 the partners of King's firm in New York—Cowan, Liebowitz & Latman, where he started as an associate in 1994—elected him chairman. The elevation pulled him into oversight of administrative matters on compensation, hiring, policy and recently, a move into fancy new digs on West 47th Street. Although a boutique with only 40 lawyers, Cowan Liebowitz represents name clients like Major League Baseball, Donna Karan, Aventis Pharmaceuticals, J. Crew and Universal Music, giving King's left-side brain a lot to keep track of.

King's modest corner office gives no hint of his musical persona—though it also doesn't display his framed diplomas from Princeton University (Phi Beta Kappa) and Harvard Law School (where he was classmates with Barack Obama). A recent visit found stacked boxes of fruit roll-ups, evidence in a trade secret case he's been handling for longtime client Promotion in Motion, makers of Welch's Fruit Snacks. On his desk sat bound briefs filed before the U.S. Court of Appeals for the Second Circuit; on the wall hung an artist's sketch of King delivering his opening statement to jurors in a novel trademark case involving dashboard car fresheners (he won).

King's colleagues are unfazed by his jazz commitments. Cowan partner Richard Mandel has heard King play only once in 23 years of working together and admits jazz is not his thing. But he calls King, with whom he's double-teamed on numerous cases, “a brilliant lawyer—the total package. He's a superb brief writer and great strategist who also has outstanding courtroom skills handling witnesses, juries and judges.”

King's clients likewise give him four-star reviews. Ellen Horowitz Dale, general counsel at Allendale, New Jersey-based confectionary manufacturer Promotion in Motion, has worked closely with King in several major trade secrets cases involving the company's signature fruit snack products, including a dispute against Hershey and another matter against a global candy brand.

“Cowan is by far the best firm we've worked with and Jonny is the principal reason,” she says. “In our case against Hershey the company threw a ton of money and resources against us, with a large trial team from Kaye Scholer, but Jonny simply ripped them apart with his courtroom abilities and his sharp analysis of trademark law supporting our case. He's so smart and really understands our business, but is also incredibly unpretentious and down-to-earth. If there's such a thing as a swinging trial lawyer, Jonny is it.”

In straddling two worlds, King belongs to a small circle of jazz musicians who've led accomplished dual-track careers. Best known is pianist Denny Zeitlin, a Johns Hopkins-educated psychiatrist who for decades has maintained a thriving practice and teaching load in San Francisco while producing three dozen albums and touring to international acclaim.

There was drummer Pete La Roca, a firebrand who played with John Coltrane, Sonny Rollins and Freddie Hubbard but disappeared from the scene in 1968 to pursue a law degree at New York University. He returned a decade later, performing under his given name, Peter Sims, and even won a copyright lawsuit against a record label for re-releasing one of his albums under Chick Corea's name. And these days, clubs in Washington feature a pianist-lawyer named Andrew Adair, who's also a Capitol Hill lobbyist for a physicians' trade group.

More than a performer, King is also a gifted writer about jazz, having authored a highly praised “insider's guide” called “What Jazz Is” (Walker Books). It begins with an enticing scene-setter:

Years ago, I returned to my college dorm room, nearly comatose from another insufferable Renaissance history class. I put on “Relaxin' with the Miles Davis Quintet,” dropped the needle on “If I Could Write a Book,” and lay down on our secondhand sofa. Red Garland's eight-bar intro, Miles' muted statement of the melody, John Coltrane's roaring solo—I was instantly transported away from lectures, exams and crummy furniture, and my head was bobbing with the pulse of Paul Chambers' bass beat. Something about that record has always rescued me, no matter from where or what.

One could be forgiven for wondering whether the demands of King's legal career or hobbies, which include fly-fishing excursions to Oregon, Colorado, Belize and elsewhere, have dimmed his piano chops or his rapport with other musicians. One would be dead wrong. During his most recent appearance at Mezzrow in late October, performing with a trio that included bassist Ira Coleman and veteran drummer Victor Lewis, King's playing was fluid and fiery, his technique in top form, with storytelling solos that zigged and zagged in sync with his bandmates, never mind that they'd had only one rehearsal. He burned through sets in which his own intricate tunes mixed with classics by Horace Silver and Herbie Hancock, along with an inspired solo mash-up of “Danny Boy”-meets-”Fiddler on the Roof” and “Shenandoah” that would have pleased the great Bill Evans.

“Jonny's not big on rehearsing,” says bassist Coleman, noting he hadn't worked with King for years prior to their Mezzrow reunion. “But his playing is so evolved and proficient, his command of styles so strong and his stage presence so relaxed, that you're in the flow together from the first bar. It put a smile on my face to reconnect with him. There was that wonderful combination of familiarity and newness you can only achieve with a first-rate musician. That's Jonny.”

King never considers which of his callings is the A-side or B-side. “Practicing law is my vocation, but I never stop playing piano or thinking about music, any more than I could stop breathing oxygen or speaking English,” he says.

King grew up in four-child household on New York's Upper East Side. His father was a family physician and mother Ruth King a travel agent (her entrée into booking that fateful jazz cruise). Like his two older sisters, Jonny King started lessons on the family's Baldwin spinet but blew them off after teaching himself Scott Joplin's “The Entertainer” from “The Sting” when he was nine. “We were addled at first he wasn't interested in classical, but learned to love jazz watching how excited he got discovering the music on his own,” Ruth King says.

By the time he got to high school, Jonny King was polished enough to perform frequently, first at school assemblies, then at bar mitzvahs and weddings. He was booked on a BBC show playing alongside piano legends Earl Hines and Mary Lou Williams.

“I wasn't a prodigy but could improvise and find my way around chord structures, mostly from reconstructing what I heard on records,” he says. It helped that a friend was the daughter of Modern Jazz Quartet pianist John Lewis—King used the MJQ rehearsal studio to tool around, though he took instruction from a teacher named Tony Eless, an alumnus of Woody Herman's band who helped him with theory, chordal harmony and how to transcribe tunes.

“Tony instilled that reverence for the language of jazz—I got to appreciate the oral history of the music and find my voice,” he says.

It was at Princeton that his performing flourished. “I was as much a professional musician as a college student, gigging constantly at clubs in Philadelphia, Trenton and Newark, as well as Princeton's eating clubs,” he recounts, getting name pros from New York to join him and earning $800 a night for his groups. And yet his grades never suffered, even when working five nights a week. He credits that feat with being an English major and an ability to produce papers on little sleep.

Law school was no surprise. King had the professional drive, and he notes, “jazz conservatory programs didn't interest me.” But he took a year's deferment from Harvard to return home and focus on music, including studying with one of his idols, pianist Mulgrew Miller.

“We never looked at a sheet of music, but sat side by side at the Baldwin in our apartment and shared lines,” he says. “I'd watch him play bass and riff on top and then we'd switch positions. It was a magical connection, and my parents loved him. Mulgrew was a gentle, wonderful person.”

As the year advanced, more opportunities fell into place, including a tour in Spain and then suddenly, an invitation to audition for singer Betty Carter for an upcoming national tour. Known as a stern taskmaster, Carter helped launch many pianists' careers—among them, Cyrus Chestnut and Benny Green. A stint as her accompanist would be a major-league ticket, but King had to decline the tryout.

“My parents had just sent our first tuition installment to Harvard and the law school didn't have a two-year deferral, so it didn't make sense to go see Betty, even knowing what I might have passed on,” he says. Not that the music stopped. Even as an overworked 1L, King secured a Thursday-Friday stint at the Charles Hotel's Regatta Bar in Harvard Square, for $90 a set. “I was actually getting more playing time than a lot of guys I met from Berklee,” he says, referring to Boston's renowned jazz college.

King also made a mark at Harvard, and not just for performing with the Black History Month band. By his third year, developing an interest in intellectual property law, he identified a legal gap he felt personally: the lack of copyright protection for improvisational jazz.

The fact that jazz involved spontaneous composition, along with styles and phrasing co-opted from other musicians who quoted one another, and was also a collaborative art form created by contributing authors (soloists), made it harder to assign copyright than other forms of music.

King wrote a paper, “The Anatomy of a Jazz Recording,” in which he outlined how a jazz quintet's version of an old standard tune could contain nine separate copyrightable elements, only one of which reflected the original composer or publisher. The article drew interest from the American Society of Composers, Authors and Publishers, which published it in its annual Copyright Law Symposium, heady validation for a fledgling IP lawyer.

(For the record, King recalls taking classes with Barack Obama and seeing the future president at some of his gigs, though they weren't friends.)

After graduating cum laude in 1991, King spent a year clerking for Massachusetts federal Judge Douglas Woodlock (who now holds senior status on the bench), then decided to try the straight-and-narrow as a litigation associate at one of Boston's old-line firms, which he prefers not to name. He knew instantly it was a mistake. “A morbidly obese partner yelled at me to fetch him files and everyone seemed shell-shocked,” he recalls.

But something else triggered him to quit after less than a year. King's live-in girlfriend Rosanna Graham, who was pursuing graduate studies at Harvard Divinity School, was battling breast cancer (the two had met at Princeton). “Rosanna died on July 27, 1993, and I packed it in right then and quit.” Having saved $20,000 from his playing, King “blew it all” on an extended fly-fishing trip to South America before returning to New York later that fall.

“I needed to produce something creatively, for Rosanna, and to prove that I had it,” he says. The result was an album on upstart label Criss Cross called, aptly enough, “In From the Cold.” Released in January 1994, it featured mostly his own compositions with a quintet fronted by two emerging saxophonists, altoist Mark Turner and tenor Vincent Herring. Not a blockbuster, ”Cold” did receive favorable reviews. One critic called King “a player and composer to watch.”

Clubbing around New York he found a recurring spot at Bradley's on University Place, the primo hang-out for the city's top pianists. King would glance up from his bench and see the likes of Cedar Walton, Kenny Barron, Tommy Flanagan, John Hicks, Joe Zawinul and other heroes sitting at the bar. Still, he acknowledges, “Those gigs didn't cover the rent,” which is why he felt lucky to hook up with Cowan Liebowitz, where he was assigned to copyright and trademark cases.

“It was nuts at the beginning,” he recalls. “Bradley's last set might end around 3:30 a.m, I'd rush home for a couple of hours sleep and get to the office by 8:30.” It got even nuttier when eight months into his job King was approached by tenor sax phenom Joshua Redman—himself a Harvard grad who had turned down Yale Law School—to join him on tour when his standing pianist couldn't make the trip. Rounding out the quartet would be up-and-comers Christian McBride and Brian Blade on bass and drums.

“I couldn't turn this one down,” King says, especially since Redman had helped research his “Anatomy of a Jazz Recording” article when they were friends in Boston. “I went to our chairman and asked for a leave of absence, which I knew was over the line. Cowan was already being awfully flexible around my music. But shockingly his response was, 'We want you to be happy.'”

The tour with Redman (a four-month, three-continent whirlwind that included consecutive-night shows in Sao Paulo, Brazil, and Paris), was a triumph of three rising jazz superstars and one second-year associate. It gave King the nerve to go back to his boss when he returned to propose a part-time work schedule: eight months in the office, four months on music.

“I guess that was an unusual request, but our firm was ahead of the curve in encouraging a work-life balance, plus Jonny was an exceptional talent,” remembers Bill Borchard, Cowan's former chair who still practices as senior counsel. “He was so passionately involved with his music, I believe it helped him become a better lawyer. The thing about Jonny is, he never looks like he's actually working.”

With that unexpected blessing, King was able to take months-long breaks each year to concentrate on jazz, securing dates at the Blue Note, Smoke, Iridium, Jazz Standard, Birdland, Sweet Basil and other top New York clubs, as well as colleges, festivals and concert venues across the United States, Europe and Asia. He played with tenor sax legends George Coleman and Eddie Harris and was called as a sideman for friends' albums. Thumbs-up reviews piled up from The New Yorker, The New York Times and various jazz sites. He saw his tunes recorded by respected players including bassist Dave Holland, pianist Renee Rosnes and vibist Steve Nelson. The rest of the year he was full-throttle on litigation and client work, although he continued to compose constantly.

“I don't know what I would have done had the firm said no—probably turned total jazz pro,” he says. “They certainly won my loyalty and gave me the best of both worlds. My first year as a full-time lawyer wasn't until 2006.” By then, he had two young daughters, Cece and Lila. King met his wife, Jacqueline Sailer—where else?—at Bradley's. A former securities class action lawyer, she quit practice in 2011 to become a professional photographer and currently teaches yoga to inmates at Riker's Island.

“Once the girls were born, I stopped hanging out so much at clubs, and didn't like being away for stretches,” King says, a key reason his appearances shrunk to a tighter radius of venues closer to home. After a while, the scales started to lean toward the Cowan side.

One thing that hasn't slipped is King's plugging away at the shortcomings of copyright law as applied to jazz. Updating his original Harvard paper, King gives frequent presentations through CLE programs, most recently to a group of 100 trial lawyers at the Federal Bar Council Fall Retreat in October. Moderated by Denny Chin, senior judge of the U.S. Court of Appeals for the Second Circuit, the event was a performance of sorts, with King and trio mates Ira Coleman and Victor Lewis demonstrating the ways in which jazz still falls through the cracks of conventional copyright framework. One of King's record label clients has asked for an in-house workshop on “Copyrighting America's Classical Music.”

King continues to contend that copyright law has “somehow forgotten about jazz,” because of “both the idiosyncrasies of jazz—an improvised, collaborative form of music—and the Copyright Act's rigid inability to adjust to those idiosyncrasies,” he writes his paper. “In truth, the business of jazz has evolved almost in spite of copyright law, so that pragmatic concerns of getting paid for your gig or recording overwhelm what the law technically provides.”

“That was an eye-opener for me,” says Coleman of the Bar Council session. “Jonny showed the lawyers how, by laying down a different beat, harmony or melody, jazz musicians are reinventing a work in every performance, even on a well-known standard. How do you protect a solo, an arrangement, or a rhythm in a broadcast or recording? So much of the legal language around music copyright is still tied to a traditional classical or pop perspective, not from the artistic standpoint of the improvisers, who likely are not being remunerated for their contributions. I came away half-thinking, maybe I should have gone to law school, too.”

With a heavy trial load and law firm to run, King nonetheless plans to be more visible at the keyboard in 2018, starting with a regular gig the last Tuesday of every month at Luca's Jazz Corner, housed in a cozy Upper East Side restaurant called Cavatappo Grill.

“It's just an upright piano but they have a nice scene and it's a block from my apartment—I'll do trios and mixed group sets,” he says. He hopes to do another album, nudged on by his publisher, eager to get more of his many tunes into circulation. And he already has another two-night appearance set in April at the super-intimate Mezzrow on West 10th Street.

However, there is one standing gig King continues to wave off, as he's done year after year: Cowan's annual holiday party. “I think we have budget to hire someone else for that,” he says. “Of course, I like to say it's because the firm can't afford me.”

Allan Ripp is principal at Ripp Media, a press relations firm in New York. He has not represented people or firms included in this piece.