OCTOBER 09: Robert Plant and Jimmy Page attend the premiere of 'Led Zeppelin: Celebration Day' at Ziegfeld Theatre on October
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Almost two years after a copyright infringement lawsuit was leveled at Led Zeppelin over "Stairway to Heaven," the case has been deemed trial-worthy. The complaint comes from the estate of Randy Wolfe, a.k.a. Randy California, the Spirit guitarist who wrote "Taurus" four or five years before that eternal song debuted on Led Zeppelin IV.

The trial will start on May 10 in L.A.; Jimmy Page and Robert Plant are the defendants. U.S. District Judge Gary Klausner had the following to say about the songs' contested similarities, per the Washington Post:

“While it is true that a descending chromatic four-chord progression is a common convention that abounds in the music industry, the similarities here transcend this core structure. For example, the descending bass line in both 'Taurus' and 'Stairway to Heaven' appears at the beginning of both songs, arguably the most recognizable and important segments. … Additionally, the descending bass line is played at the same pitch, repeated twice, and separated by a short bridge in both songs. ... Enough similar protectable expression is here that the issue of substantial similarity should [proceed to the jury]."

In 1997, the year Randy California died at age 45, the guitarist called the song "a ripoff," telling a journalist that Zeppelin "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. Maybe someday their conscience will make them do something about it.”

Francis Malofiy, a lawyer for Randy California's estate, tells Reuters, "This case, from our perspective, has always been about giving credit where credit was due, and now we get to right that wrong."

Listen to Spirit's "Taurus" and Zeppelin's "Stairway to Heaven" below: