Sheeran took the stand in a lawsuit by the heirs of Gaye’s co-author, Ed Townsend, who claim he lifted melody, chord progression, harmonies and rhythm from the older song for his 2014 Grammy-winning “Thinking Out Loud.” Earlier in the day, a lawyer for the Townsends claimed Sheeran’s live performance of a “mashup” of the two songs shows how similar they are and is the “smoking gun” proving Sheeran ripped off “Let’s Get It On.” 

“If I had done what you accuse me of doing, I would be quite an idiot to stand on a stage in front of 20,000 people and do that,” Sheeran said.

The trial, which began Tuesday in Manhattan federal court, is being closely watched by the music industry, which has seen judges and juries wrestle in recent years with how to draw the line between musical building blocks available to all and the complex combination of elements that go into a copyright-able song.

Sheeran was called to the stand by lawyers representing Kathryn Griffin Townsend, the biological daughter and heir of singer, songwriter and producer Ed Townsend, who died in 2003, and the estates of two other family members. He was frequently combative with lawyer Keisha Rice, particularly when she interrupted his answers, claiming they weren’t responsive.

“Am I allowed to answer the question that you’re asking me?” he asked in frustration at one point.

Rice questioned Sheeran about the mashup video, part of which was played for the jury. He said he often performs mashups of different songs and that many familiar hits are constructed from the same collection of musical elements, allowing them to be played together. He pointed to the many mashups of the Beatles’ “Let It Be” and Bob Marley’s “No Woman No Cry.” 

“It’s quite easy to weave in and out of songs,” Sheeran said.

Earlier in the day, Ben Crump, another lawyer for the Townsend heirs, called Sheeran a “British upstart” who profited unfairly from Gaye’s and Townsend’s 1973 classic.

“This case is simply about giving credit where credit is due,” Crump told jurors in his opening statement.

Heirs of Townsend, who died in 2003, are seeking unspecified damages from Sheeran, Atlantic Records and Sony/ATV Music Publishing. If they are found liable in this trial, a second proceeding will be held to determine damages.

Sheeran claims “Thinking Out Loud” sprung from a discussion between him and his writing partner, Amy Wadge, about elderly relatives who had lost spouses after decades together. Wadge, who’s not named in the suit, is also expected to testify in the trial. Sheeran stepped down from the stand after testifying for about an hour. He’ll be called by his own lawyers later in the trial when they present his defense to the infringement claim.

“‘Thinking Out Loud’ is about finding everlasting, unconditional love,” Ilene Farkas, a lawyer for Sheeran, told the jury in her opening statement. The lyrics and melodies of the songs are “very different,” she said. And while both songs use a similar chord progression, so do many other popular songs, including some by Buddy Holly, the Beatles and the Beach Boys, Farkas said.

The song is a work of “independent creation,” not copying, she said. “Ed Sheeran and Amy Wadge have been wrongly accused here.”