By Mesfin Fedakdu, Music Writer

NEW YORK (AP) --

What do Mark Ronson and Bruno Mars' "Uptown Funk," Sam Smith's "Stay With Me" and the Chainsmokers' "Closer" have in common?

Yes, they dominated the charts, sold millions of singles and achieved international success in the last two years. But all three smashes also extended writing credit to older songs after they were compared to earlier hits.

More and more, artists are giving that credit in the wake of the "Blurred Lines" case, where Robin Thicke and Pharrell were ordered to pay $5.3 million last year to Marvin Gaye's children after a judge said "Blurred Lines" copied their father's hit "Got to Give It Up." The decision is being appealed.

Ed Sheeran is currently in a legal battle over his slow burner "Thinking Out Loud," a monster hit in 2015. The family of Ed Townsend, the co-writer of Gaye's "Let's Get It On," claimed Sheeran's song sounds too much like the soul classic. Producer Jake Gosling and co-writer Amy Wadge are also named in the suit.

"The song was written by Ed and Amy and that song was completely far away, not even close to what we were doing when ('Thinking Out Loud') was recorded and I'm sure when they wrote it. …I was very surprised and a bit shocked by it," Gosling, a frequent Sheeran collaborator, said of the lawsuit. "I think the claim is ridiculous and really doesn't have any standing in terms of what that song is about."

Sheeran's lawyers are attempting to dismiss the case.

Other acts, though, have worked it out outside of the court room.

The Chainsmokers' Grammy-nominated "Closer" – the longest running No.1 song of the year with 12 weeks on Billboard's Hot 100 chart – recently added writing credit for Isaac Slade and Joe King of the rock band the Fray; some said "Closer" sounded like 2005's "Over My Head (Cable Car)."

The writers of the Gap Band's "Ooops Upside Your Head" were added to Ronson and Mars' "Uptown Funk," which spent 14 weeks at No. 1 last year, while Tom Petty and Jeff Lynne were added to the list of writers of Sam Smith's "Stay With Me" after it drew comparisons to Petty's "I Won't Back Down," co-written by Lynne. Both "Uptown Funk" and "Stay With Me" won the record of the year Grammy.

Mars called the Smith-Petty resolution "beautiful."

"That's artist-to-artist," said Mars, who spoke to the AP before he and Ronson were sued in October by the rights owners of the 1980s band Collage, who allege that "Uptown Funk" improperly copied Collage's "Young Girls" (Mars and Ronson's lawyers have not yet responded to the case).

"That's the way it should be. 'Hey man, come holler at me about this,'" Mars continued. "Now, they're buying up publishing like it's real estate so they basically have people out there looking for anything, three notes that sound alike and you're going to get some kind of notice from your lawyer, and it's just a dangerous place to be in creating music, because … you don't want to make music thinking about that kind of stuff.

"It's a fuzzy thing that's happening and I hope it doesn't go too crazy," he added.

Diane Warren, a Grammy, Golden Globe and Emmy-winning songwriter, echoed some of Mars' thoughts: "It's kind of a buzzkill right."

Warren doesn't agree with the "Blurred Lines" decision because while she said the production was similar, the song wasn't the same as Gaye's "Got to Give It Up."

"If you sit down and play the songs on the piano, they're not remotely the same the song," she said. "When you're in an era when you're being sued over production, it just opens the floodgates of something dangerous really."

But Warren warns musicians to be careful, too.

"I'm always writing all the time and if something sounds similar … if I come up with something really good … I'll go like, '…Does it sound like something?' And I have people I'll test it out on. If something's too close, I'll change it," she said.

Gosling, who has also produced for One Direction and Shawn Mendes, worries about the creative process being affected.

"I work in a very unconscious way in that aspect – you're writing a song, it just flows and comes out, and then sometimes afterward you do go, 'Whoa, maybe that's a bit like that?'" Gosling said. "But it's not like you're going in to copy it, 'cause that's not what we're doing here. I'm pretty sure with the majority of people that's not the case. So I'm hoping and praying it doesn't turn into that because it will stop a lot of things happening basically."

Warren, an eight-time Oscar nominee, does not believe there are distinct similarities between "Let's Get It On" and "Thinking Out Loud," which won the Grammy for song of the year earlier this year.

"That song doesn't sound anything like the Marvin Gaye song, you know, melodically. If you're going to sue for chord progressions, every song on the radio is going to be sued," Warren said, laughing. "It can get a little crazy."

But The-Dream, who has co-written and co-produced hits for Beyonce, Rihanna, Kanye West and others, says he believe Sheeran's song borrows from Gaye's.

"When you're a musician, you know where certain (stuff) comes from," The-Dream said. "I can tell whether you have taken something or whether the drum production inspired you. It's one thing to be inspired. It's another thing to take almost everything. Cut it out. Nobody is fooled.

"Most of the times, artists don't know. A lot of artists aren't into credit anyway," added The-Dream, who has won four Grammys. "I'm a part of that last regime where people like to credit others and believed in looking at the credits. You can't just take a record I gave you and just put it out. It's like, 'Why you do that? You (messing) with my money.' People from the '70s probably don't have that much trickling in."

AP Writer Jonathan Landrum Jr. in Atlanta and AP Entertainment Writer Anthony McCartney in Los Angeles contributed to this report.

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