LONDON - Peter Oxendale, a one-time glam rocker ("We all have skeletons," he says), is perhaps the world's leading forensic musicologist, the person musicians call when they believe someone has ripped off their work. In a penthouse overlooking the English Channel, he analyses songs, everything from pop hits to classical pieces, until he is sure there has been an infringement, or not.
So it's a shame he clammed up recently when asked about today's highest-profile copyright question: Did British pop star Ed Sheeran steal from Marvin Gaye's Let's Get It On for his own Thinking Out Loud?
Asked his opinion of the case, which is now the matter of a lawsuit in New York, Oxendale pretended to zip his mouth. Did that mean he had a client on either side?
"I may or may not be involved in a case featuring a pop star whose name I couldn't possibly mention," he said.
Oxendale's reticence to discuss ongoing cases - he won't even show journalists his office in case they stumble across notes - is evidence of one truth about the world of music copyright: There can be a lot of money involved.
Oxendale takes on around 450 cases a year in which musicians are liable for "thousands, hundreds of thousands, even millions of pounds", he said. "The duty of care's quite terrifying."
Last year, a jury awarded Gaye's family US$7.3 million after deciding that Robin Thicke's hit Blurred Lines copied one of his songs. Oxendale was involved in the case, though he wouldn't say how, and said the verdict was appalling.
"Those songs only share a groove," he said. "A jury can say the sky is green, but that doesn't mean it is." He expects it to be overturned on appeal.
Oxendale got into the profession by accident.
He grew up in Hull, a port city in northern England, and was set to become a music teacher until he answered an ad for an "image-conscious keyboard player" ("I had a wispy beard") and soon found himself touring America with glam-rock acts. He thought he was set for a life of private jets and five-star hotels, but then, just as suddenly, punk came along.
"I couldn't get arrested," he said. "I was a long-haired rock 'n' roll fossil playing in pubs on Friday nights to get money."
One day, he visited a publishing company to sell them some songs when its head of legal affairs spotted him.
"He said, 'Oxendale, you've got a music degree, haven't you? Can you do me a report?' And I was absolutely skint so said 'yes'. I wrote seven pages in long hand. I didn't know anything about copyright. It must have been absolute garbage."
In the 35 years since, Oxendale, 64, has built his knowledge largely by "getting beaten up by barristers and judges" in cases involving everyone from Bruce Springsteen to Bjork.
He's even been asked to use his skills outside copyright, once representing a suspected getaway driver in a murder trial. The British police had charged the man with conspiracy to murder, partly because he managed a rap group whose songs were filled with violence. Oxendale was hired to prove there were similar lyrics in countless rap songs.
Many forensic musicologists seem to have stumbled into the profession.
Guy Protheroe is musical director of the English Chamber Choir, a leading conductor and an arranger for rock bands. He seems to barely have time to take part in legal cases. But he got into it in the late 1980s when a friend and collaborator, Greek musician Vangelis, was accused of plagiarising someone's work for his Chariots Of Fire theme.
Protheroe had a music degree from Oxford University and so Vangelis' lawyers felt Protheroe had the qualifications to convince a judge that Vangelis had written a similar melody to Chariots Of Fire long before the tune he was accused of stealing had appeared.
Protheroe has kept taking cases ever since, partly for the intellectual challenge, but also because he enjoys being exposed to new music. He's recently taken on ones involving styles like dubstep and "bhangra hard-core" ("I had never heard of it before and haven't heard of it since," he said). Once he even took a case that involved researching the originality of lyrics in grime, a British rap genre.
"Whatever style it is, you still need the same intellectual approach and analysis to work out if there has been any copying," he said. "It even helps me with my own music: hearing something new and thinking, 'Gosh I've never thought of doing that with an instrument.'" "Obviously, I don't copy anything," he adds.
There are some younger forensic musicologists. Oxendale is training his son to be one. In Boston, there is Joe Bennett, 47, the dean of the Boston Conservatory, part of the Berklee College of Music, who spends spare evenings doing copyright work. He's mainly hired by advertising agencies to ensure their songs do not accidentally copy anything.
"'Accidentally' in quote marks," he said with a laugh, because some advertisers seek to have music sound as close as possible to existing music without crossing the copyright line.
Bennett said he has been analysing songs since he was five, growing up in an ex-mining village in Derbyshire, England - "I was working out Beatles' tunes with one finger on a piano" - but said he got the skills needed for his work by playing in cover bands. To avoid buying sheet music, he transcribed hits by ear, a skill he still sometimes uses to compare, say, two melodies.
People often hear similarities between songs when no copying has occurred, Bennett said. That should not be a surprise. Most songwriters follow a strict set of rules - songs being three to four minutes long or having four beats to a bar - so there is actually much scope for similarity. But the truth is that many songwriters do use other people's music for inspiration.
"Society's become enamoured by the romantic myth of creativity," he said. "The idea that inspiration comes to us in a genius-like way from God or the spirit or whatever. Often for songwriters, that is how it feels emotionally. But, of course, every songwriter is partly a product of their influences. Allowing yourself to be influenced by a song - just not copying the melody, chords or lyrics - is perfectly fine. I mean, isn't that what songwriting actually is?"
Oxendale agrees. "A lot of famous songs have been created using reference tracks and there's nothing wrong with that," he said. "There would be no Beethoven without Haydn. Who would want to have lost his music?"