"Stairway To Heaven" Plagarism court case

zep is unquestionably great, but has a long history of putting their names on other folks' tunes (or traditional songs) and, to my knowledge, already paid off for "dazed and confused" and "bring it on home." they also had to change the credit on "baby i'm going to leave you" to the actual writer, anne bredon, some 20 years later. not sure of the legal disposition of "lemon song" or "whole lotta love," but they're straight howling wolf/willie dixon cops. as for the intro to "stairway," i dont doubt that zep heard the spirit song first, but it's much more ambiguous as to whether zep crossed the line from "influence" to outright infringment. it's probably bad policy to draw the line too rigidly--almost everybody borrows elements from other songs, and in this specific case (as oppossed to :my sweet lord") the overall concepts of the songs  were sufficiently different to give this one to zep.