"In the EU and some other countries, copyright lasts for the life of the author(s) plus 70 years; since Patty Hill died in 1946 the copyright in these countries will expire following December 31, 2016, if it is presumed that its copyright is valid. However, in the United States, the song will not pass in to the public domain until 2030 based upon the law as it stands."
Dans la source 11 (désolé j'ai tappé dans le source, le site accepte pas la copie de texte hahahaha...) :
The Chicago-based music publisher Clayton F. Summy Company, working with Jessica Hill, published and copyrighted "Happy Birthday" in 1935. Under the laws in effect at the time, the Hills' copyright would have expired after one 28-year term and a renewal of similar length, falling into public domain by 1991. However, the Copyright Act of 1976 extended the term of copyright protection to 75 years from date of publication, and the Copyright Term Extension Act of 1998 added another 20 years, so under current law the copyright protection of "Happy Birthday" will remain intact until at least 2030.
Pour les US et leurs extentions, hip hip hip... ouais non rien c'est surement copyrighté aussi.