The 'Happy Birthday' song was under copyright until 2016

'Happy Birthday to You' was composed by sisters Mildred and Patty Hill in 1893 as a classroom greeting song called 'Good Morning to All'. The lyrics were separately published in 1912, and Warner/Chappell Music claimed copyright ownership from 1988, charging up to $150,000 to use the song in films and TV. Filmmakers routinely substituted other songs for 'Happy Birthday' to avoid the fee. In 2016, a federal judge ruled that Warner/Chappell had no valid copyright — the 1935 copyright only covered a specific piano arrangement, not the melody. The song entered the public domain, and Warner settled the resulting class-action lawsuit for $14 million.

Source: Brauneis, Copyright and the World's Most Popular Song, Journal of the Copyright Society (2010)