Mark Volman and Howard Kaylan of The Turtles

Mark Volman and Howard Kaylan of The Turtles perform at Seminole Casino Coconut Creek on June 15, 2013 in Coconut Creek, Fla.

Larry Marano/Getty Images

Nearly half a century after pop group The Turtles released the chart-topping hit "Happy Together," two of the members are about to take center stage in a different kind of arena: California federal court.

For the past three years, Mark Volman and Howard Kaylan, known as Flo & Eddie, have been fighting a legal battle on behalf of artists who created songs prior to Feb. 15, 1972 — the day the federal government granted copyrights to music.

These pre-1972 sound recordings are a centerpiece of digital channels like SiriusXM Radio's '60s on 6 — but until recently, rightsholders weren't being compensated because the tunes weren't federally protected. So Flo & Eddie filed several class action lawsuits against Sirius to seek vindication under state laws.

Read more: New York's Top Court Hears Turtles' 'Happy Together' Dispute Against Sirius XM

So far in the California fight, U.S. District Judge Philip Gutierrez has already granted summary judgment in the duo's favor, finding Sirius' use of the music violates public performance rights.

Battles in New York and Florida have seen split results. Sirius is currently appealing a Turtles victory in the Empire State; meanwhile, the 11th Circuit has asked the Florida Supreme Court to rule on an appeal to the Sirius win there.

Sirius paid $210 million last summer to settle the issue of pre-1972 recordings with the major record labels, which resolved the dispute for some members of Flo & Eddie's class. 

In just a few weeks, the former Turtles' frontmen will take on Sirius in California to determine what damages, if any, are owed to the remaining class members.

Flo & Eddie are represented by Henry Gradstein, along with his colleagues from Gradstein & Marzano and attorneys from Susman Godfrey. An Oct. 7 court filing argues that because the court has already found liability on claims relating to public performance of the works, Gradstein will not pursue the claims that Sirius improperly duplicated, reproduced and copied the recordings. The amount of damages being sought has been redacted, but is tied directly to the satellite company's local subscriber revenue.

"Sirius XM’s gross revenues related to pre-1972 recordings from California subscribers can be calculated on a class-wide basis by multiplying, for each period during the damages period, (1) Sirius XM’s gross revenues by (2) the percentage of performances of pre-1972 recordings on its service; and (3) multiplying the result by the percentage of Sirius XM’s subscribers located in California," writes Flo & Eddie attorney Steven Sklaver.

Read more: SiriusXM May See Its Digital Royalties Nearly Double If New Proposal Is Greenlit

Flo & Eddie also want the court to issue an injunction that would require Sirius to license pre-1972 recordings moving forward or, alternatively, issue an award of future damages based on revenue projections. (Read the full filing here.)

On the other side, Daniel Petrocelli is leading the battle on behalf of the satellite music giant. He argues that Sirius openly and continuously performed the songs for more than a decade without any complaint from class members and The Turtles won't be able to prove that any of them were damaged.

"[M]any class members — including Flo & Eddie — wanted and even actively encouraged Sirius XM to play their pre-1972 recordings by sending promotional copies, imploring DJs to increase airplay, and making appearances on Sirius XM to promote their music," Petrocelli writes. "The reason is clear: class members benefited from Sirius XM’s airplay through increased record sales and artist exposure." (Read the full filing here.)

Trial is set to begin on Nov. 15, with the final pretrial conference scheduled for Nov. 7. 

Petrocelli is pulling double duty with November trials. He's also representing Donald Trump in the Trump University class action, which is set for trial Nov. 28. He had asked Gutierrez to push back the Sirius trial to January to give him more time to prepare for Trump, but the judge denied his request. Petrocelli then turned to U.S. District Judge Gonzalo Curiel to ask for a delay in the Trump trial, but that request also was shot down.

This article originally appeared in THR.com