Copyrighting Your Music
Copyright law is essentially the same in most countries. For composers, it serves as a protective measure, granting you exclusive rights to your music. By holding copyright, you control the reproduction and distribution of your work. You also authorize its use in public performance. Basically, when you copyright your music you are safeguarding your work. Once you've filled out the correct forms, paid the filing fee, and submitted your score(s) to the copyright office, others cannot use your work without your express permission; this may or may not include royalty fees paid to you.
There are some limits to your control, however, and this can lead to legal disputes. When litigants wrangle over intellectual property rights, the doctrine of “fair use” is often cited. “Fair use” laws make allowances for certain artistic works to be reproduced or utilized under specific conditions. Disputes often boil down to how much of your work has been appropriated and for what use(s).
You cannot copyright an idea, so don't waste your time registering a description of a piece of music you are composing. Send only completed scores or phonographic recordings to the copyright office. In the United States, you may not receive a response letter for many months but your copyright takes effect upon receipt of materials.
The law also allows others to create “derivative” works. This provision is debatable in court, since the distinction between a derivation and a “near reproduction” can be hazy. Lastly, there is a statute of limitations on your copyright. Long after you're dead, your work will become “public domain.” In most countries, your copyright is protected for 70 to 120 years after your death.