Strictly speaking, once you announce that you have copyrighted something, you have the copyright on it. The same applies to trade marks and service marks: put TM (for trade mark) on your product name, or SM (for service mark) on your service name on your business cards and letterhead, and you own that trade or service mark. This is how the law was originally written, and how it remains today, a very "power to the people" law. Put your name on a document you created all by yourself, and announce on the document that you have copyrighted the work in your name, and you have the copyright on that document. Filing for trade mark protection merely means that you've convinced the federal government that you are the first one to use the given trade or service mark to signify your product or service. If you don't file for trade mark or service mark protection, any legal battles over who owns your trade or service mark will have to be fought by you all on your own, without the direct assistance of the federal government telling the judge that you had already proven to the federal government that you were the rightful owner of the trade or service mark.