Kanye West's "Golddigger" (originally by Leonard Cohen)

I was investigating (see: 'looking up on Wikipedia') the Leonard Cohen song "Hallelujah", and I came across the song's coverage. Turns out the song has been covered by about two-dozen artists, and how a majority of the covers are actually secondary and tertiary covers (so that's covers of covers, and covers of a cover's cover, respectively). On top of that, the lyrics change considerably between interpretations, with artists picking and choosing (and adding) lyrics as they see fit.

Now as I'm reading this, I'm naturally imagining someone akin to Kanye West passing off a song like "Golddigger" as a 'loose artistic interpretation and essential cover of 'Hallelujah' reflective of the times'

I mean, how much do I have to modify a song before it's not a cover anymore? A little more scholarly inquiry (see above definition of "investigating") reveals that there are special cases of Copyright law that govern 'derivative works'. A derivative work must be "...sufficient new expression, over and above that embodied in the earlier work for the latter work to satisfy copyright law’s requirement of originality."

I'm pretty sure that Kanye West has heard Jeff Buckley's cover of John Cale's cover of Cohen's song 'Hallelujah', and that had indirectly (or directly) inspired him to create a ballad about the perils of love and infatuation, reflective of the parent work (of course, Mr. West maintains that this isn't the case, but I think we know better).