On Friday, U.S. district judge Gary Klausner ruled that while there is no evidence of a "striking similarity," Led Zeppelin's classic "Stairway to Heaven, bears enough resemblance to "Taurus" by Californian rock band Spirit for a jury to decide on a possible breach of copyright.
The L.A. court must now rule whether the British rockers ripped off the opening tabs of "Taurus" for their most famous song, which Judge Klausner called "arguably the most recognizable and important segments" of the two tunes.
The jury's task, Klausner added, is to make "a subjective assessment of the 'concept and feel' of two works," according to court papers obtained by Entertainment Weekly.
A trial is scheduled for May 10.
The copyright lawsuit itself was brought against Page, 72, and Plant, 67, in 2014 by Michael Skidmore, a trustee for Spirit's late songwriter Randy California – real name Randy Wolfe.
It revolves around the period between 1968 and 1969 when Spirit and Led Zeppelin occasionally toured together, and where Page and Plant would have heard "Taurus" played numerous times.
It wasn't until 1970 that Page and Plant wrote "Stairway to Heaven" for the untitled album often referred to as Led Zeppelin IV. The record has since sold more than 23 million copies and is ranked as the fourth bestselling album of all time by the Recording Industry Association of America.
While "Stairway to Heaven" has never been released as a single, the album is estimated to have raked in royalties approaching $600 million.
Skidmore can expect to receive a healthy percentage of these should he win the case, although Judge Klausner stated that the trustee could get only 50 percent of any damages awarded, citing a contract signed by Randy California in 1967.
"It's been a long time coming," Skidmore's attorney Francis Alexander Malofiy told The Guardian.
"This case, from our perspective, has always been about giving credit where credit was due, and now we get to right that wrong."
This isn't the band's first time in the courtroom. Allegations of plagiarism involving artists from folk singer Bert Jansch to Joan Baez have dogged the group for years, and they've paid settlements to Willie Dixon (and added him as a cowriter) and Ritchie Valens' publisher for "Bring It On Home," "The Lemon Song" (for Dixon) and "Boogie with Stu" (for Valens).
A rep for Led Zeppelin declined comment on the case to EW.