Pop star and singer-songwriter Ed Sheeran is being sued for plagiarizing Marvin Gaye's classic hit "Let's Get It On" for his chart-topping 2015 song "Thinking Out Loud."

The heirs of Gaye's co-writer on the tune, Edward Benjamin Townsend, have filed a lawsuit accusing Sheeran of stealing elements of the track for his own composition.

Kathryn Townsend Griffin, Helen McDonald and Cherrigale Townsend filed the copyright infringement lawsuit in the United States District Court in the Southern District of New York, accusing the artist of "unauthorized reproduction, distribution and/or public performance of the Plaintiffs' copyrighted musical composition "Let's Get It On" (Let's) using the hit song, "Thinking Out Loud" ("Thinking"), written by Amy Wadge and Ed Sheeran and subsequently recorded by Ed Sheeran."

This is the second copyright infringement lawsuit filed against Sheeran this summer. In June, court documents were filed accusing the singer-songwriter of plagiarizing Matt Cardle's song "Amazing," recorded by the X Factor UK winner in 2009, for his song "Photograph."

The lawyer in that suit is none other than Richard Busch, who ironically won a huge plagiarism lawsuit on behalf of the heirs of Marvin Gaye for another classic song by the artist. That track was of course the huge 2013 hit for Robin Thicke, "Blurred Lines," co-written by the singer and producer Pharrell Williams, which was found by a judge to be a copy of one of Gaye's another popular song, "Got To Give It Up."

While that case seemed more clear-cut because of strikingly similar elements in "Blurred Lines" and "Got To Give It Up" that could be heard by most music fans, the similarities between "Thinking Out Loud" and "Let's Get It On" are more subtle. While the lyrics and melody of Sheeran's tune are quite different, the lawsuit accuses Sheeran of lifting the famous bass line and rhythm of the Gaye song:

"The harmonic, melodic, and rhythmic elements of composition ... have made this song one (1) of the most famous songs in R&B history and soul music history ... Let's begins with an iconic melody, harmony and rhythm that are recognized around the world. The prominence of the bass line and drum composition throughout Let's make these compositional elements qualitatively important to the musical work as a whole."

Unfortunately for Sheeran, he has already acknowledged some connection between the tunes by performing them together in concerts, which is pointed out in the body of the suit in order to bolster its accusations.

It's interesting to note that this lawsuit has been brought exclusively by the heirs of Edward Benjamin Townsend and not by the heirs of Marvin Gaye. Whether Gaye's family intends to bring a separate lawsuit is not clear, although there is a likelihood the two would be combined by the court, which will ultimately determine whether Sheeran's song is a copy.

What do you think? Listen to the two songs below and let us know your verdict in the comments section.