Led Zeppelin's lawyers have asked a judge to throw out a case accusing the band's songwriters of ripping off a riff for Stairway To Heaven.
Their attorney Peter Anderson said that the estate of Randy Wolfe, founder of the band Spirit, failed to prove it owned the copyright to his 1968 song Taurus or that it was substantially similar to the famous Stairway song.
He wrote in a motion to dismiss: "Plaintiff rested and failed to carry his burden of proof on multiple issues."
US district judge R Gary Klausner is expected to hear arguments on the motion when the trial resumes later.
Randy's estate claims that guitarist Jimmy Page and singer Robert Plant incorporated a unique musical phrase from Taurus in the introduction to their 1971 rock epic - arguably the British band's most famous song.
Randy, who performed as Randy California, died in 1997.
Mr Anderson said attorney Francis Malofiy had failed to show that members of Led Zeppelin were familiar with the song and experts had not presented a convincing case that the tunes were similar enough to amount to copyright infringement.
Musical experts for the Wolfe estate said there were many similarities between the obscure instrumental Taurus and Stairway, but a defence expert testified last week that the main similarity was a common descending chord sequence used as a musical building block for 300 years.
Mr Anderson also said the plaintiff failed to show actual damages from any infringement or present evidence of revenues from Stairway.
An economist testified that Led Zeppelin works that include Stairway To Heaven earned nearly 60 million dollars (£40.9 million) in revenues in the past five years, but that included other works as well, and did not include manufacturing costs or other expenses that could be deducted.
Mr Anderson asked Judge Klausner to make the judgment before the case goes to the jury. The motion is fairly typical after the plaintiff rests in a case.