Courts don't care about harmony. Most US courts follow a guideline that the copyrightable parts of a composition are melody and lyrics. Nobody has ever successfully sued for stolen chord progression.
And apparently arpeggios, because the US District Court of California ruled in Flame vs Katy Perry that arpeggios are "melodic enough" for copyright protection.
A combination of chords, melody, rhythm are I think the only reasonable measure that a song has been copied.
If I take the entire melody of a Beatles song, including the verse and chorus, but set it to an entirely different chord progression, would the court recognize that as an original song? What if I lifted all of the lyrics as well?