For all those interested in the much awaited outcome, here is a really great article on Led Zeppelin vs. Wolfe (as the Spirit band member Randy California), whose estate sued Zeppelin for the instrumental opening of “Stairway to Heaven”. Wolfe’s estate claimed that it was very similar to the opening of their song “Taurus”.
Here is a statement from US Copyright law: According to U.S. copyright law, in the absence of a confession, musicians who accuse others of stealing their work must prove “access”—the alleged plagiarizer must have heard the song—and “similarity”—the songs must share unique musical components. though it is difficult to come to a definition of what is “similarity”.
Led Zeppelin attorney Peter Anderson kept a cool demeanor. He argued that the Wolfe Trust did not own the copyright to the song (a claim the judge shot down) and that the musical characteristics Malofiy claimed Zeppelin copied were musical traditions that date back at least to the 1600s and appeared in songs like the Beatles’ “Michelle.”
Here is more information in the complete article by Kory Grow: from ROLLING STONE Magazine