Have we run out of new songs?

By now, everyone with a pulse and access to a device that plays music is familiar with Sam Smith’s “Stay With Me”—the ubiquitous hit that has gone platinum four times, has nabbed two major Grammy nominations, and continues to linger in the upper echelons of the Hot 100 nearly a year after its release.

But to some ears the song sounds even older. Many listeners have noted the soulful ballad’s melodic similarities to Tom Petty’s 1989 rock chart-topper “I Won’t Back Down.” Last week, it emerged that Smith’s legal team had acknowledged the resemblance— but added that Smith and co-writers James Napier and William Phillips were “not previously familiar” with Petty’s song. In fact, back in October the 22-year-old Brit’s publishing company gave songwriters Petty and Jeff Lynne co-writing credits on the track, along with a reported 12.5 percent of its royalties (though it doesn’t entitle either to a Grammy should “Stay With Me” win Song of the Year on Feb. 8, per Recording Academy rules).

Petty isn’t holding any grudges. “Let me say I have never had any hard feelings toward Sam,” he said in a statement. “All my years of songwriting have shown me these things can happen. Most times you catch it before it gets out the studio door but in this case it got by. Sam’s people were very understanding of our predicament and we easily came to an agreement. The word lawsuit was never even said and was never my intention.” Smith’s rep agreed, telling EW in a statement, “Although the likeness was a complete coincidence, all involved came to an immediate and amicable agreement.”

It’s hardly the first time a hit song has echoed Petty’s sound (or others’—see sidebar). Back in 2006, there was much chatter about the Red Hot Chili Peppers biting his “Mary Jane’s Last Dance” for their “Dani California,” but when asked about the similarities, Petty told Rolling Stone, “A lot of rock ‘n’ roll songs sound alike. Ask Chuck Berry. The Strokes took ‘American Girl’ [on 2001’s ‘Last Nite’], and I saw an interview with them where they actually admitted it. That made me laugh out loud. I was like, ‘OK, good for you.’ It doesn’t bother me…. I think there are enough frivolous lawsuits in this country without people fighting over pop songs.”

Sara Bareilles seems to share Petty’s philosophical take. When fans pointed out that Katy Perry’s 2013 single “Roar” bore a strong resemblance to Bareilles’ “Brave,” the latter shrugged it off. “People really felt like Katy was ripping me off, and I disagree,” Bareilles told EW last year. “Katy is a friend of mine, and it seemed like there was this infusion of people wanting to create conflict and drama. I find that to be really fatiguing.” Even more recently, there has been online chatter about Kelly Clarkson, whose brand-new single “Heartbeat Song,” from her forthcoming seventh album, was widely noted on blogs for its similarity to the 2001 Jimmy Eat World hit “The Middle.”

Which isn’t to say these disagreements can’t get ugly—as the ongoing battle between Robin Thicke and the estate of Marvin Gaye over Thicke’s 2013 summer smash “Blurred Lines” shows. In the yearlong walk-up to the trial, which is slated to begin Feb. 10, the two sides have sniped at each other repeatedly over whether Thicke borrowed too heavily from Gaye’s 1977 song “Got to Give It Up.” The leaked depositions of Thicke and co-writer Pharrell Williams led to a lot of embarrassing revelations about both parties: Thicke admitted he was barely involved in the creation of his biggest hit, and Williams gave a lot of cryptic answers to simple questions, including that he liked Gaye because “he’s an Aries.”

When such cases go all the way to court, two things need to be proved: that the writers of the song in question were familiar with the composition they’re accused of copying, and that the similarities are too notable to be accidental. The second criterion can get a little tricky. Though forensic musicologists are often brought in, scientific research and analysis go only so far. “For all the lawyering, what it comes down to is people sitting in a jury box thinking, ‘Do those two songs sound alike?’ ” explains Nashville-based copyright lawyer Ramona DeSalvo. “That’s what it comes down to, because the test is, essentially, the ordinary observer: Would the ordinary observer comparing the songs think they sound alike?”

The court of public opinion isn’t a legal one, of course, but thanks to the music industry’s ever-dwindling sales revenues, cases like this may become more common in years to come. Album sales were down 11 percent last year, with download sales on a particularly steep decline as on-demand streaming services like Spotify and Beats Music continue to take over the digital space.

With that in mind, high-profile musicians are protecting their work in ways that would not have occurred to them even a decade ago. Beyoncé and Rihanna have both made noise about the unsanctioned use of their images and work (Rihanna just won a $5 million suit against Topshop after the brand sold a shirt with an unauthorized image from her “We Found Love” video on it). And Taylor Swift recently applied for trademarks on a handful of phrases from her blockbuster 1989 album, including “this sick beat” and “Nice to meet you. Where you been?”

She couldn’t claim “Shake it off,” though. That trademark was already owned by global health-care conglomerate GlaxoSmithKline—proving that even Taylor isn’t bigger than Big Pharma.