An author who has studied and chronicled how rock musicians pilfer melodies and riffs would side with Spirit in its current case against Led Zeppelin and “Stairway to Heaven.”

“At most it’s a quarter of the song, but the plaintiffs did a good job of proving (Jimmy Page and Robert Plant) knew about Spirit,” says Tim English, author of Sounds Like Teen Spirit: Stolen Melodies, Ripped-off Riffs, and the Secret History of Rock and Roll. “When they were jamming on ‘As Long as I Have You,’ the Garnett Mimms song, they were including part of ‘Fresh Garbage’ in the jam and that’s on the same album (as “Taurus”). It stretches belief when they say they didn’t know Spirit’s music.”

English will not be surprised if a jury—now in its second day of deliberations—finds in favor of the estate of Randy California. After the experts testify about the similarities between the guitar riffs in the two songs, “the jury is left with ‘what’s your opinion?’ A lot of these cases don’t go to court because it’s a David vs. Goliath situation and you don’t know how a jury will respond. Here’s a guy who was too destitute to file suit when he was alive …. and a band that had to revise a lot songwriting credits as a result [of lawsuits]. This is a song that generates millions of dollars each year.”

Should Page and Plant lose the case, English suggests there are plenty of songs they could go after. He contends Black Sabbath’s “Paranoid” rips off “Communication Breakdown,” Heart’s “Barracuda” owes a lot to “Achilles Last Stand” and the melody of Pearl Jam’s “Given to Fly” nicks “Going to California.”