All of us know that as an artist, you cannot use lyrics or melodies from a previously composed song if it is under copyright. Sometimes you can’t even perform or play a recording of a copyrighted song in public! Individuals and corporations can pay a great deal of money to ensure that their music cannot be illegally distributed. BUT, did you know that a copyright is not necessarily permanent?
I have recently discovered that copyrights tend to expire depending on the initial amount paid for the copyright and when the music was copyrighted. Any copyright granted since 2002 is valid for 70 years after the death of the creator. If the copyrighted work is held by a corporate entity, it expires 120 years from the date of creation or 95 years after the date of publication, whichever comes sooner. Because copyright information and fees are subject to change based on legislative decisions, it is important to consult the U.S. Copyright office for the most current information.
(Read more: What Is the Music Copyrighting Process? )
Once a copyright has expired, the composer’s/performer’s music has entered public domain, where the music and lyrics are available for anyone to borrow, alter, or rearrange.
It is important to check the public domain so that you can avoid copyright infringement. It is even a good idea to have proof that the music you are using is considered part of the public domain, just in case anyone is suspicious. Here’s a helpful fact for all of you who are curious about what music is safe to use – music that was copyrighted in 1922 or earlier is automatically placed in the public domain, unless otherwise noted.
For more information regarding copyright laws, visit this link at Public Domain Music.
Happy composing!
Studio 220 
Thanks for posting this. It is very useful information that I will take into consideration.
As much as I understand the reason for copyright laws, it seems that a law prohibiting the use of a melody or lyric from a copyrighted tune is a little vague. Where is the line drawn that makes two melodies exactly the same, thus breaking the law? It just seems kind of silly to me.
so how does that factor into whenever a band covers another band? or Glee for that matter?
You can get permission from the copyright holder to cover their music. But only then is it appropriate to recreate as well as resell copyrighted music.
You can get permission from the copyright holder to cover their music. Only then is it appropriate to recreate or resell copyrighted music. The process of approval can be tough at times, depending on the popularity of the song or artist. I have never attempted it myself, but I would imaging you would need a lot of patience. :]