Song lyrics are copyrighted, and music publishers are notorious for being litigious. With that in mind, there are a few things you can do to potentially mitigate a publisher instituting a copyright infringement lawsuit against you.
Fair Use
Fair use is a defense to a copyright infringement lawsuit. Courts typically review four factors as to whether your use is fair. They look at why you’re using the lyrics, whether the work you’re taking is creative or factual in nature (here, songs are creative so that factor is likely not in your favor), how many lyrics quantitatively and qualitatively you’re taking, and whether your use is taking away any potential licensing markets from the music publisher.
Let’s assume factor two is against you given the creative nature of song lyrics. Now let’s look at the other three factors. How you use the lyrics, the amount you take, and if you use them commercially will help determine if your use is fair.
If you use lyrics in an academic book, that is a favored purpose; however, using lyrics to set the scene in a novel likely won’t be favored. In addition, analyze whether your use is transformative. Are you adding new utility or meaning (like analyzing lyrics in an academic book) or are you simply copying and pasting the lyrics into your novel? Next look at how much you’re taking. Is it one line or half the song? Regardless one line may be too much if it’s the heart of the work (perhaps here if it’s a popular refrain). Finally, analyze whether you’re using the lyrics in a commercial work. Are you writing a novel or a textbook? Context matters.
There are no guarantees. Fair use is determined on a case-by-case basis, so the only real way to know if a use is fair is if it goes to federal court. If you want to avoid it, be cautious and call a lawyer.
Public Domain
Songs published in 1926 have now entered the public domain, so anything in 1926 and before is free to use.
Song Titles
Song titles are not copyrightable, so they are free to use. However, make sure that the song title is not trademarked.
Common Phrases
Phrases commonly used in everyday life that happen to be lyrics may also be okay. For example, having your character reply “I know” likely won’t mean you’ll get sued by a musician who sings those words in their song.
Nevertheless, context matters, so if you are unsure, contact an attorney. As a literary lawyer, I routinely help authors with their fair use questions. If you have any questions, don’t hesitate to reach out.