Thanks, that's fascinating. At least from a cursory search (https://www.google.com/search?q=are+public+playlists+copyrig...), conclusive case law doesn't seem to exist in the US. In the UK, the one case I found was settled (https://www.theguardian.com/technology/2014/feb/27/spotify-m...) and didn't address an app/company attempting to enforce a copyright license received when a user created a playlist. It's not clear in either jurisdiction, but like you said, litigation is definitely possible.