Here’s how songs, especially hip-hop and R&B songs, are made today : the framework is built in the studio by a producer, working on some combination of keyboard, drum machine, sampler and computer program. Songwriters contribute topline melodies and conceptual ideas, and sometimes all the words. Generally speaking, at the moment of creation, there is no sheet music, no notation that’s meant to guide musicians.  On Tuesday, a federal jury in Los Angeles concluded that Robin Thicke and Pharrell Williams, the performer and primary songwriter-producer of the 2013 pop hit “Blurred Lines,” committed copyright infringement by using elements of the 1977 Marvin Gaye song “Got to Give It Up” in their composition without proper credit. The jury awarded Mr. Gaye’s family approximately $7.3 million, a combination of profits from the song and damages. That’s an attention-getting amount of money, but the verdict itself is far more damning.  Owing to the specifics of copyright law, the jury was instructed to base its decision on the sheet music, a fact that reflects how inadequate copyright law is when it comes to contemporary songwriting and production practices. In 2015, the arrangement of notes on a sheet of paper is among the least integral parts of pop music creation. We’re decades beyond the time when a songwriter penned a tune on paper, then gave it to musicians to perform.  Besides, in an age in which popular music is incredibly diverse, with more sonic references, instruments and digital trickery available than ever, using sheet music as a measure of a song’s originality is a weak tactic, and possibly an irresponsible one. The “Blurred Lines” verdict is a victory for an outmoded law, but also an outmoded way of thinking about music.  There are untold things that static sheet music can’t capture: tone, feel and intensity or texture, all of which are as important to modern songwriting as the notes, and probably more so. Relying on the sheet music exposes a generational bias, too — implicit in the premise of the case is that Mr. Gaye’s version of songwriting is somehow more serious than what Mr. Williams does, since it is the one that the law is designed to protect.  There is, it should be said, a similarity in the bass lines of the two songs, and perhaps, more broadly, in their shared lite-funk feel. And it’s likely that Mr. Thicke and Mr. Williams didn’t help their case by contending in interviews around the song’s release — including one in The New York Times — the psychic and literal debts they owed Mr. Gaye, and specifically “Got to Give It Up.” (Mr. Thicke testified, though, that he had barely any input in the writing of the song, a different explanation from what he gave the news media.) Often in the credits that come with an album, the phrase “contains an interpolation of” will appear. That generally means the song borrows from something else, but in a way that’s less than an actual sample or a heavily repurposed lyric or melody. It can feel like a legally codified version of a good-will gesture — certainly “Blurred Lines” might have benefited from such a designation up front.  But in truth, once you begin splitting hairs, the possibilities are endless — listen closely to “Got to Give It Up,” and you may hear the skeleton of a song like Prince’s “Kiss.” Will the Gaye family sue him, too?  In the “Blurred Lines” trial, Marvin Gaye’s family accused Robin Thicke and his co-writers of using distinct musical elements of Mr. Gaye’s 1977 hit “Got to Give It Up” without permission.  Disagreements of this nature are typically settled out of court. Take the recent case of Sam Smith’s “Stay With Me,” which owes a songwriting debt to Tom Petty’s “I Won’t Back Down.” At least, that’s what Mr. Petty and his fellow songwriter Jeff Lynne contended, leading to a quick and clean settlement in which they would be added to the song’s writing credits and granted part of the royalties  The argument there was structural — both choruses have a similar pace and syllabic emphasis. But Mr. Smith’s song is ecstatic and soaring, and Mr. Petty’s is quietly tenacious. “Stay With Me” is far more indebted to traditional choir gospel than to Mr. Petty’s meditative country-rock.  Presumably Mr. Smith’s team agreed to a settlement to avoid disrupting his meteoric rise with a messy public lawsuit. If it had fought the claim, it might have had a case. But copyright law may be of less use to modern songwriters and producers using cutting-edge methods, who want to protect their work in the here and now. “Blurred Lines” was one of the most successful songs of 2013, No. 2 on the Billboard year-end list. But it wasn’t close to being the only popular song that fought claims of being derivative. The No. 1 song of 2013 was Macklemore & Ryan Lewis’s “Thrift Shop,” which bears at least some resemblance to Le1f’s “Wut” — both songs use synthesized sax (or saxlike) skronk in similar patterns. Le1f has openly griped about what he perceives as the unfair borrowing, but it’s likely that he has little recourse.  Or take “Fancy,” last year’s smash by Iggy Azalea and Charli XCX. It is, in almost every way, a facsimile of the minimalist Los Angeles hip-hop sound perfected over the past few years by DJ Mustard. His sound is signature — clean, bubbly synthesizer lines with certain unmistakable tones and rhythms that themselves are derived from early 1990s low-end-heavy Los Angeles hip-hop production, and according to some, the mid-2000s hyphy sound of the Bay Area. “Fancy” feels like a craven effort to profit from the DJ Mustard sound without having to pay for his services. (It was produced by the Invisible Men and the Arcade, who should be given credit for being able mimics.)  In the current context, this imitation is a more meaningful sort of infringement than what’s at play in the “Blurred Lines” case, but contemporary copyright law would seem to have less to offer a creator like DJ Mustard, whose bailiwick is everything but the notes. Like him, whole generations of songwriters may remain vulnerable, their innovations implicitly less valuable because no one’s figured out how to adequately write them down.  A version of this article appears in print on March 12, 2015, on page C1 of the New York edition with the headline: A Verdict Based on an Old Way of Making Music. Order Reprints| Today's Paper|Subscribe
In basing its verdict on sheet music, a critic argues, a jury in Los Angeles ignored how songs are actually created today.