Warner Bros. claims they own the copyright on “Happy Birthday To You” for 100 years (meaning their claim will expire in the 2030s if the laws are not revised once again to extend ownership).
Of course it is clear that “Good Morning To You” (which Happy Birthday’s melody is taken from) is much older than 100 years.
And there are persons who are still alive who lost ownership of their songs decades ago (or were never compensated even when money was owed by thieving labels like Atlantic). If “anyone” could release the songs, the artists could release their own “signature” edition and still make some bank on their work.
100 year copyrights only serve the interests of the few corporations that own the bulk of the material.
Modern copyright law is immoral and unconstitutional (I don't really give a rat what the Nasgul say)