For the singer Katy Perry the weekend has surely brought relief, with the resolution of a plagiarism claim that had dragged on for eight years. A California court ruled on Friday that she will not now have to pay the rapper Flame (real name Marcus Gray) £2.1m in compensation for the use of a nine-note sequence in one of her hits. But Ed Sheeran, the Halifax-born musical superstar, is not enjoying the same relief. He remains embroiled in the defence of the latest of a string of alleged breaches of copyright. He has treated lawyers to an impromptu performance of a Nina Simone tune to make a point about the essential building blocks of a song, and will return to the High Court in London this week. Such unpleasant, high-profile legal tussles have now become part of the burden of being an A-lister, a kind of humiliating occupational hazard for the elite group of international musicians who regularly bring out tracks that make them yet another fortune. “People only come for you like this if you have written a really huge song. Only a tiny minority are in this hallowed realm, with billion-streaming songs,” said Guy Chambers, who composed some of Robbie Williams’ biggest hits with him, including Angels and Let Me Entertain You. “Although claims are getting more common, it’s not going to happen to many people. Early on in my career I heard the old industry saying, ‘where there’s a hit there’s a writ’, and it’s true.” Chambers and Williams were in the line of fire together once. They went through a legal wrangle over Jesus in a Camper Van, a track from the platinum-selling album I’ve Been Expecting You. “So far I haven’t really had a dispute over the music. The case Robbie and I had was about lyrics, where it tends to be slightly more clear cut,” Chambers said. Williams and Chambers lost the case and a judge ordered that 25% of income generated by the song be paid to Ludlow Music and that it be dropped from future copies of the album. Sheeran, together with co-writers Johnny McDaid and Steve Mac, are continuing to defend themselves against the accusation that they stole an eight-note refrain from the relatively unknown grime act Sami Switch, real name Sami Chokri. The case centres on the hook line of Sheeran’s 2017 hit Shape of You which, it is claimed, has a “striking similarity” to the chorus of Chokri’s 2015 single Oh Why. Sheeran, 31, denies pinching the musical phrase and told the court last week that he had not heard Chokri’s song until he learned of the claim. Four years ago, in a preemptive swoop, Sheeran and his fellow songwriters asked for a legal declaration that they had not infringed any copyright, but months later Chokri and his own co-writer, Ross O’Donoghue, made a claim for damages and “an account of profits in relation to the alleged infringement”. It is not the first time for Sheeran. Claim has followed claim recently in a predictable chain that must take some of the pleasure away from being hugely popular and immensely wealthy. Sheeran and McDaid, perhaps best known as a member of Snow Patrol, have already added the names of the writers of TLC’s No Scrubs to their credits for Shape of You due to discovered musical similarities and have also settled a case fought over their song Photograph. In addition they have paid out to the X Factor winner Matt Cardle over the song Thinking Out Loud. But last week McDaid angrily rejected the suggestion that such legal dealings indicate he “was in the habit of consciously or subconsciously appropriating the skill and labour of other songwriters during my songwriting and recording sessions”. Dua Lipa is another performer to be threatened by two expensive lawsuits, both over her song Levitating. Songwriters L Russell Brown and Sandy Linzer have claimed the opening melody of Levitating is a “duplicate” of some of their work. To back up their arguments they pointed out that Lipa openly admits to having “emulated prior eras” to create her sound. The American reggae band Artikal Sound System has also filed a suit claiming that Levitating is close to their 2017 track Live Your Life. And, of course, the mighty Taylor Swift has been dogged by an unsuccessful claim that her song Shake it Off was partly plagiarised. (Swift is open to a bit of early fair dealing. In advance of the release of her song Look What You Made Me Do her lawyers approached the British band Right Said Fred because of a resemblance suddenly detected to their jokey hit I’m too Sexy. The pair got a percentage of the writers’ credit.) The case that first raised the musical stakes, the yogic granddaddy of pop plagiarism cases, was the one Beatle George Harrison came to refer to as “the worst experience of my life”. In February 1971, while his solo hit My Sweet Lord was still high in the charts, he was sued by Bright Tunes Music Corp over the track’s similarities to The Chiffons’ He’s So Fine, a popular song put out a decade earlier. The case crawled on for years and a judge eventually found Harrison guilty of “unconscious plagiarism” because it was deemed likely that he would have heard The Chiffons’ tune. It is a creative syndrome now known as “cryptomnesia” and is pretty hard to guard against. Indeed Harrison, who had happily admitted that My Sweet Lord was consciously inspired by a 1968 version of Oh Happy Day, was so distressed by the plagiarism tag that he later told reporters he was paranoid about composing. “I thought, God, I don’t even want to touch the guitar or a piano in case I am touching somebody’s note.” Perry’s case last week revolved around her song Dark Horse, coincidentally the name of a Harrison 1974 solo album. Gray had sued her back in 2014 and won, but the verdict was later overturned. On Friday an appeals court upheld the decision, suggesting that to do otherwise would have stifled creativity. Industry expert Chris Cooke, founder of UnLimited, believes the ruling indicates that American courts, in this case the crucial Ninth Circuit, may be behaving more cautiously: “I hope there is an understanding now that some musical segments are going to appear in other places. Although it will be fascinating to see if there is a similar caution in the UK with the Sheeran case.” Chambers would welcome greater freedom for musicians: “If I was in the hit-making game now, rather than writing musicals, I would feel pressurised.” Like many songwriters he worried about the impact of the Blurred Lines case, when Robin Thicke and Pharrell Williams were found guilty of merely copying “the feel” of Marvin Gaye’s song Got to Give it Up. Mike Smith, president at Downtown Music Services, believes his job as a music publisher is to protect his artists’ copyright, but he is generally wary of litigation, which he regards as an expensive American habit that mainly benefits lawyers. Musicians will always borrow ideas, Smith understands, but if those ideas are still in copyright then a “there is usually an acknowledgement of what has happened”. “A member of one of my old bands came in once and played a “new” tune to us. We all immediately pointed out it was the same as Werewolves of London by Warren Zevon, which he said he had just never heard.” New algorithms on streaming services promise technology that spots closely aligned harmonics at the touch of a button and, as Cooke points out, YouTube’s Content ID already performs a similar function for music publishers and record labels. “Anything posted that uses an existing song will be detected and the owners can then choose to monetise it or block it for usage. That’s not saying, of course, that any time it detects an unexpected similarity there is a case of copyright infringement. But these developments certainly mean there’s more sensitivity.” Chambers admits if a tune he is writing sounds familiar, he sometimes uses the Shazam music recognition app to check: “It’s not a particularly good way to do it. And anyway we are all inspired by something when we start. When I wrote Angels, I was thinking of Hey Jude. Its piano part has a similar feeling, although it’s not the same chords.” Chambers admires the more relaxed attitude of Elvis Costello, whose old hit Pump it Up appears close to a new Olivia Rodrigo track. Costello simply commented on Twitter:“It’s how rock and roll works. You take the broken pieces of another thrill and make a brand new toy. That’s what I did.”