Led Zeppelin are being sued for plagiarism over their hit "Stairway to Heaven."

The band have been served legal papers on behalf of late song-writer and guitarist Randy California from the band Spirit, who claimed for years the track's opening notes were lifted from their track "Taurus." Attorney Francis Alexander Malofiy, who is representing a trust for Randy, told Bloomberg Businessweek, "It's been a long time coming. The idea behind this is to make sure that Randy California is given a writing credit on 'Stairway to Heaven.'"

Businessweek quotes an estimate that by 2008 the track had earned at least $562 million.

Spirit played shows with Led Zeppelin in 1969 and fans have talked about the similarities between the songs for years, claiming Jimmy Page used the band's riff. He allegedly wrote "Stairway to Heaven" in 1970, two years after "Taurus" was released and a year after the band shared stages at gigs across the America.

According to the band's bass player Mark Andes, Spirit always included "Taurus" in their sets: "It was such a pretty moment. It would typically come after a big forceful number and always got a good response."

In 1997, Randy went public with his claims and said "Stairway to Heaven" was a "ripoff." He said, "The guys made millions of bucks on it and never said, 'Thank you,' never said, 'Can we pay you some money for it?' It's kind of a sore point with me."

Those close to Randy say he never sued because he didn't have any money back then and the band "thought the statute of limitations was done." As Led Zeppelin prepares to release remastered deluxe versions of their original albums, including the track, Randy's trust is taking action with a copyright-infringement suit and an injunction that would block the reissue.