'Happy Birthday to You' was under copyright for 80 years — earning $2M a year in royalties

Warner/Chappell Music claimed copyright over 'Happy Birthday to You' for decades and collected around $2 million per year in licensing fees from TV shows, films, and restaurants. A 2016 US court ruling found the copyright claim invalid — the song had effectively been in the public domain since 1922. It is now officially free to sing.

Source: Good Morning to You Productions Corp. v. Warner/Chappell Music, Inc. (2016)