At least one lawyer is hoping Ed Sheeran pushes back against the estate of songwriter Ed Townsend in its claim that Sheeran’s “Thinking Out Loud” has nicked Townsend and Marvin Gaye’s “Let’s Get It On.”

To J. Michael Keyes, a partner and intellectual property lawyer at Dorsey & Whitney, the lawsuit is the latest case showing what’s wrong with music copyright law.

“This alleged infringement, the chord progression they’re complaining about, is a very basic chord progression that’s in I don’t know how many of dozens of songs you’ve heard over the years. It’s very simple, very basic,” says Keyes, a pianist who studied in the former Soviet Republic of Georgia.

“The rhythm is also very basic. There’s going to be lots of examples you can pull from this particular genre with this basic pattern. Unlike other art forms, there are certain stock ways in which you are going to lay out music that is going to be similar across genres. It’s these very basic building blocks of music that nobody should be able to have a monopoly on.”

In the lawsuit, the estate claims Sheeran and co-writer Amy Wadge copied the “heart” of “Let's Get It On” and repeated it throughout the composition, and that the drumming is also “strikingly similar.”

Keyes notes there is case support for the notion that if someone takes “the heart of a composition, even if it’s just a few notes, that is therefore actionable.”

“For my money,” Keyes said, “I look at this and listen to the tune and think it’s crazy somebody can build a copyright claim alleging these similarities. Whether this goes forward depends in large part on how aggressive Sheeran wants to be. It’s an unsettled area believe it or not.”

Part of the unsettled nature stems from Gaye-Robin Thicke “Blurred Lines” case that resulted in a multi-million dollar judgment and the “Stairway to Heaven”-“Taurus” case—will the jury be asked to compare recordings or sheet music? What’s the value of an infringement? Where does one draw the line between original and copy? “Every jury is going to see things differently,” he noted.

One key flaw in music copyright law is that “stock elements” are allowed in other art forms, but “we haven’t gotten there with music.” Keyes said it would take a string of court judgments to establish what songwriting elements all writers have access to without fear of recrimination.

“The claims are getting out of control, and this is a really good example of that,” he said. “Unless copyright laws are retooled, I suspect we’ll see more and more of these cases where heirs come out of the woodwork.”