We’re in week two of the federal court trial over Ed Sheeran’s 2014 pop hit “Thinking Out Loud” and whether or not it copied from Marvin Gaye’s classic, “Let’s Get It On.” The family of Gaye’s co-writer, Ed Townsend, has taken Sheeran to court, alleging that he stole some of the underlying musical ingredients to make his song. This case will have implications for music copyright going forward.

“Marketplace Morning Report” host Sabri Ben-Achour spoke with Jennifer Jenkins, a professor at the Duke University School of Law, for more on this. The following is an edited transcript of their conversation.

Sabri Ben-Achour: So here is a snippet from Ed Sheeran’s song “Thinking Out Loud.”

Ben-Achour: And now here is some of Marvin Gaye’s “Let’s Get It On.”

Ben-Achour: I am not a musically talented person, but how are those the same? Like, how?

Jennifer Jenkins: Well the similarities between the two songs actually come down to a pretty standard chord progression? Let me show you what they sound like in a pared down way. First, here’s the chord progression in “Thinking Out Loud.”

Jenkins: Now here’s the chord progression in “Let’s Get It On.”

Jenkins: So you can hear the similarities. Here’s the deal, though. That’s a really common, standard, basic chord progression that you find in lots of songs and a pretty unremarkable rhythm. So, if one artist can own that, then that takes an essential building block out of the toolkit for all other songwriters who want to build on the same structural substrate.

Ben-Achour: At one point in this trial, lawyers for the plaintiffs showed a video of an Ed Sheeran concert in which he moves seamlessly from playing his own song into playing “Let’s Get It On.” And the plaintiffs’ lawyer said, “That is a smoking gun.” And Ed Sheeran said, “No, a lot of pop songs,” as you’ve mentioned, “just kind of have the same chord progression.” Is there any consensus on where you draw the line of what’s infringing? And where do you think this case is gonna go?

Jenkins: I think there’s a consensus within the copyright community and possibly within the songwriting community. Artists need to be protected from copyright infringement, absolutely. We all agree on that. Another thing we agree on is that “Let’s Get It On” is one of the greatest songs ever written of all time. So that’s true. But at the same time, the law can’t and shouldn’t try to lock up basic musical building blocks, chord progressions — because if it did, we’d get less wonderful music.