I'm not sure about that. The definition of parody hinges on imitating an author or work (sometimes a whole genre), rather than on satirizing/critiquing subject matter unrelated to the author/work being imitated. He could write a song satirizing/critiquing the CIA and if it happens to imitate a song/style of Miley, then it's a parody of the latter, not of the former. Or a parody of nothing at all, in the strictest definition, since he's not satirizing/critiquing that which he's imitating.
When it comes to music copyright, certain aspects are copyrightable (therefore requiring license to use) and other aspects are not. Words and melody are (so Weird Al would need to license Miley's melody if he doesn't modify it sufficiently), but rhythm/chords/timbre/style/etc. are not (so Weird Al wouldn't need to license anything if he is merely copying those things from Miley). I think Al makes some songs with a copied melody requiring licensing, and some songs without that in which case no permission of any kind is legally necessary.
I'm not sure about that. The definition of parody hinges on imitating an author or work (sometimes a whole genre), rather than on satirizing/critiquing subject matter unrelated to the author/work being imitated. He could write a song satirizing/critiquing the CIA and if it happens to imitate a song/style of Miley, then it's a parody of the latter, not of the former. Or a parody of nothing at all, in the strictest definition, since he's not satirizing/critiquing that which he's imitating.
When it comes to music copyright, certain aspects are copyrightable (therefore requiring license to use) and other aspects are not. Words and melody are (so Weird Al would need to license Miley's melody if he doesn't modify it sufficiently), but rhythm/chords/timbre/style/etc. are not (so Weird Al wouldn't need to license anything if he is merely copying those things from Miley). I think Al makes some songs with a copied melody requiring licensing, and some songs without that in which case no permission of any kind is legally necessary.