The Song Remains The Same

A pre-trial hearing type of event has decreed that Stairway To Heaven, the iconic Led Zeppelin track might well have been copied from another song by a band who toured with them in the 60s.  This means that it will go a full trial where it will make headlines in almost all British newspapers as they debate the differences.  The plagiarism debate is quite interesting, especially where music is concerned given the almost infinite number of variables involved in a composition.  Even though the tune might be almost the same, the bass or drum backing can render it completely different.  there are also a finite number of notes/chords, so you might expect these type of cases to be more common, but they appear to be rare.  It could be because this particular song is so well known (and has therefore realised a great deal of royalties) that it might influence this case.