An anonymous reader writes
"Happy Birthday remains the most profitable song ever. Every year, it is the song that earns the highest royalty rates, sent to Warner/Chappell Music (which makes millions per year from "licensing" the song). However, as we've been pointing out for years, the song is almost certainly in the public domain. Robert Brauneis did some fantastic work a few years ago laying out why the song's copyright clearly expired many years ago, even as Warner/Chappell pretends otherwise. You can read all the background, but there are a large number of problems with the copyright, including that the sisters who "wrote" the song, appear to have written neither the music, nor the lyrics. At best, they may have written a similar song called "Good Morning to All" in 1893, with the same basic melody, but there's evidence to suggest the melody itself predated the sisters. But, more importantly, the owner of the copyright (already questionable) failed to properly renew it in 1962, which would further establish that it's in the public domain"Link to Original Source