Thanks for taking the time to learn about copyright laws in music publishing. You might think that a composer or arranger owns the rights to their music, including the right to decide how it’s used or shared. But in the world of print music publishing, that’s not always the case.  

Every print music publisher (like Hal Leonard and Alfred Music) has a contract with a composer. The composer gives up all rights to the copyright in exchange for a share of the money made from selling the sheet music. This share is usually between 5 and 10%. Here's an excerpt from one of my contracts, 

COMPOSER hereby sells, assigns, transfers, and sets over unto PUBLISHER, its successors and assigns, the work, all copyright therein, and the original manuscript now entitled:   [INSERT SONG TITLE HERE]

.... the rights herein transferred by COMPOSER to PUBLISHER shall include the sole and exclusive right:

(a) to print, publish, and sell the WORK, etc. (and skipping down to letter "e" in the contract)...

(e) to reproduce the WORK mechanically, electrically, photographically, or electronically;

(g) to license or assign to others upon such terms as the PUBLISHER may determine in its discretion