A US jury will deliberate for a second day Thursday on whether Led Zeppelin poached the opening to "Stairway To Heaven" from an obscure Los Angeles rock band.
Songwriting duo Robert Plant and Jimmy Page have denied plagiarizing the guitar introduction of their classic 1971 song from "Taurus", an instrumental track by the long-defunct 1960s group Spirit.
The case was brought before a federal court in Los Angeles by Michael Skidmore, the trustee, and friend of Spirit guitarist Randy California, who drowned in 1997 having never taken legal action over the song.
A jury of four men and four women deliberated for five hours Wednesday before being sent home by Judge Gary Klausner and asked to return on Thursday morning.
Led Zeppelin frontman Plant, 67, testified on Tuesday that he recalled writing the lyrics of "Stairway" in 1970 as he and Page sat by a fireplace in an English country manor house where the band recorded and rehearsed.
He said he was inspired to write the lines after he heard guitarist Page, 72, play the opening notes of what would become one of the most famous rock songs of all time.
The suit, which was filed by Skidmore two years ago, seeks damages and claims California deserves a songwriting credit so that he can "take his place as an author of rock's greatest song".
"Give credit where credit is due. This case has always been about credit," Skidmore's attorney Francis Malofiy said as he presented his closing arguments on Wednesday.
David Woirhaye, the chief financial officer of Rhino Entertainment -- which markets and distributes the Led Zeppelin catalog -- testified that "Stairway" had grossed $3.4 million during the five-year period at issue in the civil trial.
"We're asking for a one-third credit, a shared credit," Malofiy told jurors, asking that damages of between that amount and $13.5 million be awarded to California's trust.
The jury had been told Zeppelin opened for Spirit when the hard rockers -- Plant, Page, John Paul Jones and the late John Bonham -- made their US debut on December 26, 1968, in Denver.
But the surviving members have submitted testimony that they never had substantive interaction with Spirit or listened to 1967's "Taurus" before recording "Stairway" in December 1970 and January 1971.
Experts called by the plaintiffs say there are substantial similarities between key parts of the two songs, but defence witnesses have testified that the chord pattern used in the intro to "Stairway" is so commonplace that copyright doesn't apply.
Page told the court last week he first heard "Taurus" when his son-in-law showed him a comparison with "Stairway" on the Internet just a few years ago.
He said he only recently discovered he owned Spirit's debut album, which includes "Taurus" after checking his record collection of more than 10,000 vinyls and CDs.
Defence attorney Peter Anderson said Skidmore had not proved that the trust owned the copyright to "Stairway" or that Page and Plant had ever even heard Spirit perform in the few times the bands shared a concert bill in 1968 and 1969.
He told the jury the descending chromatic scale played by Page in the first moments of "Stairway" was a musical device so common and unoriginal that "it belongs to everyone".