The Christmas Song is protected, simple as that unless it was written over 95 years ago. Let Google be your friend:

This one is sort of a condensed version:

https://www.theatlantic.com/technology/archive/2018/04/copywritten-so-dont-copy-me/557420/

This one is the legal version:

https://en.wikipedia.org/wiki/Copyright_law_of_the_United_States

Then there are brand new developments:

http://www.copyright.com/blog/copyright-legislation-in-2018-4-pending-bills-to-know-about/

You can see why this isn't an easy thing to answer on a forum like this but your question is simple. Unless the Christmas Song can be traced back to over 75-100 years ago, it's fully protected regardless. I'm not an attorney and don't play one on TV. This is tricky stuff but I think the current law is pre 1972 songs are protected for 70 years after the death of the author. If that's not exactly right I do know one thing, it's still a long time.

My personal comment is concerning people who say songs should be public domain after 25 years or whatever. No, intellectual property belongs to the author and his family. It is and should be part of his estate and can be passed down to his heirs just like a house or anything else of value imho.

Bob

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