The Guardian publishes an article of which we quote an extract, full article here: (https://www.theguardian.com/music/) Alleged musical kleptomania seems more heavily patrolled than ever
It is not just about Sheeran; a shift in the law allowing for a case against Led Zeppelin’s Stairway to Heaven 
(which the band won), alleged musical kleptomania seems more heavily patrolled than ever. There are many questions here. Are songwriters increasingly lazy, or arrogant, or simply incompetent – or are they being unfairly chastised for a warm homage to the music they, and we, grew up with?
This week, Ed Sheeran, a pop star whose stranglehold on the UK Top 40 is so extreme that his Star Wars name would be Chart Maul, avoided a lengthy legal trial by settling a $20m (£16m) copyright infringement claim out of court, for an unspecified sum. Two writers behind Amazing, a song by X Factor hat-botherer Matt Cardle, had spotted something familiar in Sheeran’s song Photograph and, represented by the legal team who annihilated Robin Thicke and Pharrell Williams in the controversial Blurred Lines case, filed a lawsuit.
Over to Pete Townshend who, asked about One Direction’s Best Song Ever, whose opening bars were similar 
to the Who’s Baba O’Riley, released a statement saying: “The chords I used and the chords they used are the same three chords we’ve all been using in basic pop music since Buddy Holly, Eddie Cochran and Chuck Berry made it clear that fancy chords don’t mean great music – not always. I’m still writing songs that sound like Baba O’Riley – or I’m trying to.”
When that happens, they will call in a musicologist – but until it is possible to wire your brain into the Spotify database, there is a catch. “We’ll say: ‘This song is similar to another one. Is it too similar and what do we need to change?’ But to go to him in the first place, we need to have already spotted which song the new song sounds like.”
One such musicologist – a forensic musicologist, in fact, and don’t pretend you wouldn’t like that on your business card – is Joe Bennett. Does he agree with the hypothesis that pop might be running out of tunes? “In cases of melody-based plagiarism disputes,” Bennett says, “melodic probability can be used to ask: ‘How likely are two melodies to come out identically, or very similarly, through coincidence?’
Last year, indie artist White Hinterland threw a lawsuit at the team behind Justin Bieber’s enormobanger Sorry claiming that her song Ring The Bell had been used on the track. To the untrained ear, the similarity was strong. Even Diplo, who has got pretty good ears, went on record saying he thought it was a sample. Then Skrillex uploaded a video showing how he had created the hook by manipulating an ad-lib from the song’s original vocal, by songwriter Julia Michaels. The video was captioned: “SORRY but we didn’t steal this.”
But for Michaels, who has also written for Britney, Gwen Stefani and Selena Gomez, that wasn’t the end of the story. What happened next shows how unexpectedly lawsuits can play out: you might assume a potential plagiarist would get all the negative feedback, but that doesn’t account for the defensive nature of several million Beliebers. “Sonny [Skrillex] said to me, post the video [on social media] if you want, it’s your fight as much as it is mine,” Julia told me last year. “I posted it, and people thought it was me who was suing everybody!
https://www.theguardian.com/music/2017/apr/13/has-pop-finally-run-out-of-tunes-ed-sheeran-plagiarism
