Legal Question in Business Law in California

Re: Fictitious Business Name in use in Multiple States

First, registering a fictitious business name does not confer any right to use that name. It is nothing more that notice to the public that you are using, or intending to use, the name. If someone else is already using the name, your registration might be tantamount to a confession of intent to infringe.

The right to use a name that's already in use is a rather complex issue, and it's usually better to avoid it altogether, and especially if the other user or users have registered the mark first. There are limited situations in which two users can use the same mark, despite registry by one, without legal conflict, but widespread use of the internet for marketing is closing this window.

I'd advise getting a book about trademarks (a self-help law book in peperback would be fine) and if still in doubt after self-study, retain a trademark attorney.

Without detailed analysis, I'd guess it would be unwise to choose this name, even if the other users haven't officially trademarked first.