A compulsory license is an exception to copyright law that grants permission to anyone wishing to use your work, whether or not you want to grant the license.
Compulsory licenses must be issued for use in cable television rebroadcast, on Public Broadcasting System (PBS), in jukeboxes, and for digital performance of records, phonorecords, and digital recordings. The latter are referred to as compulsory mechanical licenses.
A compulsory mechanical license grants permission to anyone wishing to re-record a song that has already been commercially released. For instance, if you (or anyone else) wanted to re-record a version of “Light My Fire” (or any other song that has been commercially released), you would not need explicit permission from the Doors’ publisher, so long as they were paid at least the statutory rate (the royalty rate as defined by copyright laws) of 9.1¢ per song for each copy sold.
For more information, please follow this link to www.copyright.gov.