Rocker Jimmy Page is charged with stealing the guitar riff for the band's classic song from track Taurus written and recorded by Randy California for his band Spirit.

The late California refused to take legal action against Page and bandmate Robert Plant while he was alive, but a trustee for his estate decided to sue the pair following the songwriter's death.

Francis Malofiy, the attorney representing the estate of songwriter Randy California, also known as Randy Wolfe, ended his side of the case in a Los Angeles courtroom on Friday by focusing on how much Led Zeppelin actually made from the track, by bringing in economist Michael Einhorn to testify on the band's profits.

According to the Los Angeles Times, Einhorn used figures from record sales, digital downloads, publishing agreements and other revenue streams during a recent three-year period set by copyright law.

The exact total was unclear since Einhorn used both U.S. dollars and British pounds during his testimony and also did not deduct expense the music companies had paid. However, the sum was in excess of $60 million (£42 million).

Zeppelin's legal team argued some of the amounts Einhorn included in his findings were payments that fell outside the three-year period set by copyright law, which would have made California's estate eligible to receive revenues earned by the song.

The band's defense team also began their case on Friday, bringing in New York University musicologist Lawrence Ferrara, who believed Stairway to Heaven has no meaningful similarities with Taurus.

He specifically pointed out that both songs feature a similar descending chromatic line, but that is a common device which has been used in music composition for years, saying, "They are a musical building block that no one can possibly own."

The case continues.