Can you say “Stairway to Heavy Royalties?” You may have imagined the old Led heads, Robert Page and Jimmy Plant, sitting in a grungy garage somewhere back in the seventies striking those iconic four chords for the first time and truly crafting the song “Stairway to Heaven” from whence there was none. Now you may have to change that image and imagine them sitting in the front row of a Spirit concert feverishly jotting chord progressions down on a notepad. That’s what a former member of the band Spirit is claiming in a lawsuit over a song that has allegedly grossed in excess of $525 million.

Have you even heard of the seventies band Spirit? Apparently Led Zeppelin used to tour with them back in the 1960’s and former Spirit band members claim they often saw Page and Plant sitting in the front row at their concerts—with perfect front and center seating to rip off a catchy riff. Robert Wolfe, who wrote the song “Taurus,” which opens with the legendary riff, reportedly thought about suing for copyright infringement as far back as the 1980’s, but his family stated he could not afford it. It’s fun to ponder the type of expert vetting we might do in this case: “Did you attend Woodstock?” “Where were you in proximity to the stage?” “Were you able to grasp a true ‘concept and feel’ for the music?” You may find that comical, but that is the exact question the judge pinpointed as the key issue in this matter—“a subjective assessment of the ‘concept and feel’ of the two works”—a determination he believes he is no more qualified to make than a jury, which is why the case is going to trial.

Another interesting aspect of this case is also the age of the music. In 2016, we’re nearing fifty years since “Stairway to Heaven” was written. Meaning, the case could have wide implications for the music industry as a whole. If a ruling comes back that Led Zeppelin ripped off a copyright, it may embolden many other wayward artists out there who may be carrying a long-time grudge and feel their songs were swiped as well. In short, a ruling in favor of Spirit could potentially boost spirits and spark many copyright suits. Established record labels and big icon artists who have been raking in the royalties for decades have plenty to worry about with this trial.

Led Zeppelin has countered, claiming a descending chromatic four-chord progression is so common in the music industry that it simply cannot be copyrighted. Meaning, it doesn’t matter how obviously similar the songs may be or whether they have the same ‘concept and feel,’ because the riff is too common to copyright. If this argument holds, Spirit has nothing to protect. But if you’re playing the intro to “Stairway to Heaven” in your mind right now, I’ll bet you find it unique enough to try to defend.

If you can’t conjure the song on your own, I’ll bet you’re eager now to hear the two songs side-by-side? So is the jury. Go on. You can jam out on the job as long as it’s still considered “work.” Give it a listen.