Ed Sheeran sings in court as part of Marvin Gaye copyright case

Ed Sheeran played the chord progression to his hit song Thinking Out Loud and sang on the witness stand in Manhattan federal court on Thursday, during a trial over whether he copied Marvin Gaye’s classic Let’s Get it On.

Testifying as the first witness in his own defense to a packed courtroom, the British singer-songwriter described his process for writing the song about everlasting love in 2014, shortly after he began a new romantic relationship and after his grandfather died.

“I draw inspiration from a lot from things in my life and family,” said Sheeran, saying the song was inspired by the love he observed between his grandparents.

The 32-year-old is being sued by heirs of songwriter Ed Townsend, Gaye’s co-writer on the 1973 song.

Townsend’s heirs are seeking a share of profits from Thinking Out Loud, saying that the syncopated chord progression was copied from Let’s Get It On.

Sheeran testified for nearly an hour on Thursday, explaining how his friend and collaborator Amy Wadge started strumming the chords for the song during a visit to his home in England, and how they had collaborated on the lyrics.

On the stand, he sang the phrase “I’m singing out now”, which he said he sang during his songwriting session with Wadge. He said the phrase sounded like, “I’m thinking out loud”, which ultimately became the title.

“When I write vocal melodies, it’s like phonetics,” Sheeran said.

He then picked up a guitar from behind the witness stand, played the chord progression to the song, and sang the opening words: “When your legs don’t work like they used to.”

Sheeran told the court that he preferred to work quickly, with most of his songs written in a day, or even a matter of minutes. He said he had written up to eight or nine songs in a single day in the past.

Thinking Out Loud went to No 1 in the UK and No 2 in the US, and won a Grammy award for song of the year in 2016.

Lawyers for Townsend earlier this week showed a video of Sheeran transitioning seamlessly between Thinking Out Loud and Let’s Get it On, in a live performance they said amounted to a confession that he had ripped off the song.

In court, Sheeran replied: “Most pop songs can fit over most pop songs … if I had done what you’re accusing me of doing, I’d be a quite an idiot to stand on a stage in front of 20,000 people and do that.”

The trial was interrupted on Wednesday when one of the plaintiffs, Townsend’s daughter Kathryn Griffin Townsend, collapsed and had to be carried out of court.

Griffin Townsend fainted just as Sheeran team’s began to cross-examine a musicologist who had been brought in to testify that there was a substantial similarity between the two songs.

Griffin Townsend previously appeared as a witness, saying she intended to “protect my father’s legacy”, but added that she had brought the case reluctantly and described Sheeran as “a great artist with a great future”.

She is one of three plaintiffs, along with Townsend’s sister Helen McDonald and the estate of Ed Townsend’s ex-wife Cherrigale Townsend.

Townsend died in 2003. Gaye died in 1984.

The trial is expected to resume on Monday.

Reuters contributed to this report