On Tuesday (April 25), opening statements began after a jury was selected in a trial that will determine whether Ed Sheeran’s “Thinking Out Loud” bit Marvin Gaye’s “Let’s Get It On.”

The heirs of Ed Townsend, the legendary soul singer’s co-writer of the 1973 classic, sued Sheeran, alleging the U.K. pop star’s 2014 song has “striking similarities” to “Let’s Get It On” and “overt common elements” that violate their copyright, according to the Associated Press.

Filed in 2017, the lawsuit made it to a trial that is expected to last up to two weeks in Manhattan federal court. Sheeran is among the witnesses expected to testify, although the AP reports he was not in court at the start of jury selection.

The jury is slated to hear the recordings of both songs numerous times, however each’s lyrics and vibes are legally insignificant. Jurors will be instructed to consider the raw elements of melody, rhythm and harmony that make up the composition of “Let’s Get It On,” as documented on sheet music filed with the United States Patent and Trademark Office.

“The two songs share versions of a similar and unprotectable chord progression that was freely available to all songwriters,” Sheeran’s attorneys said of the comparison between the two songs.

Townsend’s family attorneys say in the lawsuit that Sheeran himself has segued into “Let’s Get It On” during live performances of his hit and have sought to play a YouTube video of one such performance for the jury. Judge Louis L. Stanton, 95, who is presiding over the trial, has denied their motion to include it but will reconsider after he sees the other evidence presented.