Led Zeppelin bassist John Paul Jones has testified in defence of his bandmates in the copyright lawsuit that claims the band ripped off a riff used in Stairway to Heaven.

Jones provided backup to singer Jimmy Page’s testimony that he had never met members of Spirit, despite opening for the band when Led Zeppelin made its US debut in late 1968.

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Jones maintains he owns no Spirit albums and never heard Spirit play.

The estate for Spirit’s late guitarist Randy Wolfe claims Led Zeppelin lifted a passage from the instrumental Taurus and incorporated it in the well-known introduction to Stairway.

If the estate is successful, it could be worth millions of dollars as the song continues to funnel a fortune to songwriters Jimmy Page and Robert Plant.

Jimmy Page and Robert Plant played with Spirit in the late 1960s. Photo: Getty

Led Zeppelin works that include Stairway to Heaven have generated revenues of nearly $US60 million ($A81.19 million) over the past five years, economist Michael Einhorn testified.

Einhorn, who said he reviewed 50,000 pages of financial documents to reach that figure, conceded on cross-examination that some of the revenues came from a 2008 contract covering the band’s catalogue of 87 songs.

Led Zeppelin lawyers contend the contract falls outside the statute of limitations and shouldn’t be included in potential damages.

After Einhorn testified, the plaintiff rested its case. The defence opened with a musicologist, who cast doubt on whether the two songs are substantially similar.

While experts for the plaintiff previously said there are many similarities between Taurus and the intro to the 1971 Stairway, Lawrence Ferrara said the likeness was limited.

The main trait they shared, a notable descending minor chord progression, is a common building block in songs dating back 300 years and is found throughout pop music predating Wolfe’s composition from 1967 or 1968.

“It’s not something anyone can own,” said Ferrara, a music professor at New York University.

Ferrara picked the songs apart note by note, playing the riffs on piano and comparing them to compositions such as My Funny Valentine and the Beatles’ Michelle.

Comparing differences in the arrangement of the same notes in both songs was like rearranging the letters in “treason” to spell “senator”, Ferrara said, noting that the succession of letters makes a difference.

He said similar chord pairs other experts highlighted as important was like comparing pairings of the words “and the” in one short story to another.

“That I would not call a relevant similarity,” Ferrara said.

With Page and Plant seated at the defence table for the fourth day of trial, their bandmate Jones made a brief supporting appearance.

Page has said he knew some of Spirit’s music and owned a couple of their albums, but he never heard Taurus until his son-in-law showed him comparisons to Stairway on the internet a few years ago.