Jimmy Page and Robert Plant are expected to reunite Tuesday in a Los Angeles courtroom rather than on the concert stage, defending the originality of their classic “Stairway to Heaven.” When the verdict is read, will the song publishing remain the same?

The Led Zeppelin songwriters will be defending claims from an heir of the leader of Spirit that the song’s famous guitar riff was directly nicked from Spirit’s instrumental “Taurus,” a song released in 1968, three years before the release of “Stairway.” The portion in question lasts about 10 seconds and Page and Plant could be held liable for royalty payments since 2011.

It’s the latest high-profile music copyright suit to make it to trial; last year a jury awarded Marvin Gaye’s family $7.4m over Robin Thicke and Pharrell Williams’ “Blurred Lines,” noting it was too similar Gaye’s “Got to Give It Up.”

As in that case, jurors will be asked if the compositions, rather than the released recordings, constitute copyright infringement.

Key to the argument of Michael Skidmore, trustee for the trust of Spirit leader Randy California, is that Led Zep heard the song when the two bands shared bills in the late 1960s.

Page and Plant will most likely argue that the song’s roots are in Renaissance-era music and that both tunes are connected to music in the public domain. Led Zeppelin’s lawyers are also expected to question whether the estate has the fight to sue, as California, nee Wolfe, signed over the rights to his music to a music publisher around the time of Spirit’s first album, the Los Angeles Times reported.

The trial is proceeding due to a ruling in April from U.S. District Court Judge R. Gary Klausner who noted there is a “striking similarity” between the songs.