The estate of Spirit got stupidly greedy. If they had pulled a “Blurred Lines” and tried to claim that Jimmy Page had copied the intro to “Stairway” from the recording of “Taurus”, they could have played both songs for the jury and most likely gotten a nice settlement.
Instead, their claim was that Page & Plant had heard them perform “Taurus” several times and copied the song, so they should have co-writing credit. If they’d won, they would be eligible for retroactive royalties from every time “Stairway” has ever been played or performed by any band over the past 40-some years, since they wanted in on the songwriter copyright. But because of that, the studio recording wasn’t admissible, just the sheet music! So to prove their case, they had to have a guy play “Taurus” and “Stairway” on piano in court, and they lost, because they sound totally different.
