The National Association of Teachers of Singing endorses a strict policy regarding copyright laws. The use of photocopied music is prohibited at all NATS sponsored events, from the national to the chapter level. Exceptions are:
- Music that is out of print, still under copyright law, with permission from a publisher.
- Sheet music or books for which the copyright has expired, but available in CD format. (e.g., CD Sheet Music). Performers must be prepared to present proof of ownership upon request.
- Sheet music purchased legally from an online vendor. Such music should have either a separate page proving the performer has purchased such or a copyright notice at the bottom of the music that includes the performer's name. Performers must be prepared to present proof of ownership upon request.
- Music available from approved public domain websites. Performers should take particular care when accessing these sites as some do not guarantee that all works are indeed in the public domain. Current approved online public domain sites are: