There was the whole lawsuit over Huey Lewis' "I Want a New Drug" and Ray Parker Jr.'s "Ghostbusters"
I never would have guessed that those songs were mounted on the same frame. That's what it amounts to. But unlike the Pontiac Trans Am and the Chevy Camaro, these songs to my ear are totally different songs, like a Camaro and a Mustang. Musical borrowing is as old as dirt. I think whoever makes the best (read most popular) version of a given set of chords should "win". And if they are each equally popular, that should be allowed.
Personally I'm not on board with claiming a series of soundwaves so no one is allowed to use them. To me that's like saying no one is allowed to put the words purple and bayou together except me. Puh-lease. Copyrighting a chord sequence amounts to owning that chord sequence, which is rediculous. That's like trying to own air. Air is public domain that everyone is entitled access to. If you remake a song verbatim, OK you owe the writer their due. But if I take elements of just the music part of a song...not the lyric..... and add my own "original" musical elements, including different lyrical content, and a different overall vibe, then it's a clearly different composition than the original in my mind. There are only 12 notes. The original song came from someone else in some form too, as it has from the beginning.
If someone wanted to write a very different story about a seafarers struggles with a great big whale, would the Moby Dick people sue? Sure they have whales and ships and oceans in common, but if it were a completely different story line, to me it's fair game. If someone clearly piggybacked on the idea of another, and it became popular, should this person be penalized? Let supply and demand make the rules. If a product is inferior, it won't fare well. If a product touches a nerve with the public, no matter where the idea came from, they deserve the success IMO. Everybody's ideas come from everybody else's eventually anyway. There's very few completely original things being done musically IMO.
Robert Johnson, completely lifted whole songs and put a different set of lyrics to them and he is hailed and revered and his is one of the greatest legends in the music realm. He lifted "Love in Vain" from the song "When the Sun is Sinking Low" (I think I recalled that title correctly)
Howlin Wolf lifted...but modernized...Charley Patton's "Spoonful Blues". And so on and so on. Lawyers man.