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The song was recently found to be in the public domain. See e.g. http://arstechnica.com/tech-policy/2016/02/happy-birthday-is...

Not played in the US? So no issue

copyright applies everywhere on Earth.

So, still not an issue.

Actually no it doesn't. Copyright is a legal concept enforced by laws of various countries and different countries have different laws.

"on Earth"

Kind of hard to serve papers on a non-sentient object on another planet.

(Not that that would stop lawyers if they were getting paid for it.)