some practical information today....
As you know, I write historical fiction. The manuscript I recently finished is about a travelling preacher and his family -- Arkansas, 1957.
There are songs in this manuscript. Lots and lots of songs.
So, I had to research which songs could and could not be used in writing. I thought I would share what I have learned on this subject.
Any songs written before 1922 are in the public domain. As such, you are free to use them in your writing. Performing the songs gets a bit trickier, as artists will often copyright their version of a public domain song. But, we are not singing in our books, so no worries with that. Songs post 1922 and/or under copyright can only be used with the owner's permission.
It is easiest to go to one of the Public Domain websites like this one here or even this one here. They have lists of songs pre 1922 that are assumed to be in the public domain.
Second, it helps when you contact an agent/editor to be able to say "I have researched the songs referenced in this manuscript and confirmed they reside in the public domain." See how smart you will sound? They'll be dying to work with someone as professional as your sweet self.
What the US Copyright Office has to say
"Under the fair use doctrine of the U.S. copyright statute, it is permissible to use limited portions of a work including quotes, for purposes such as commentary, criticism, news reporting, and scholarly reports. There are no legal rules permitting the use of a specific number of words, a certain number of musical notes, or percentage of a work. Whether a particular use qualifies as fair use depends on all the circumstances."
What is fair use? Unfortunately, that is not cut and dry. I venture to say use in a novel would not likely fall under 'fair use'.