Robert Plant and Jimmy Page of Led Zeppelin are facing a copyright lawsuit after a judge ruled Friday that the question of whether the opening riff for Stairway to Heaven was pilfered from another band can go before a jury. CNN reports:

The lawsuit was brought by a trustee for the estate of the late Randy Wolfe, also known as Randy California — a songwriting member of the American rock group Spirit.
The suit claims that the arpeggiated guitar introduction to “Stairway to Heaven” — widely viewed as one of the all-time great classic rock songs since its release in 1971 — infringed on the copyright of the instrumental “Taurus,” released on Spirit’s debut album three years earlier.

[…]

The suit, filed by Wolfe’s trustee Michael Skidmore, claims Page may have drawn inspiration for the smash hit after hearing Spirit perform their song at three U.S. festival performances at which both bands appeared prior to the release of Led Zeppelin’s track.

The judgment notes that Page said he had never seen a Spirit performance.

So, denial aside, it is at least possible Page could have heard the Spirit instrumental before he wrote Stairway to Heaven given that both bands were at the same festival. How similar are the riffs themselves? Here’s a video that plays them back to back:

As similar as that video makes things sound, it’s worth noting that the chords are not exactly the same. If you want an in depth comparison, this guitarist has done one. He plays each song (and several similar songs) and notes that while the chords are not exactly the same the bass line, the rhythm and the overall sound are strikingly similar.

It’s hard to listen to the two songs knowing Page could have heard the earlier work by Spirit and not wonder if he did at some point. And yet, you have to also say that the Spirit song was never, ever going to be a rock classic. Even if Page did hear it, he also improved upon it. It’s the difference between Salieri and Mozart. I’ll close with this BBC interview in which Jimmy Page describes how he and the band put together Stairway to Heaven: