Trademark at state level?

Filing a DBA has nothing to do with your business name being trademarked.

California does not have a trademark process. You have to do that with the US Patent and Trademark office.

In theory, a trade name in California should prevent others from REGISTERING a similar name as trademark. But registration of trademarks is completely optional in the USA, so someone could use a similar brand without any reference to your company. You would have to find them and sue them to make it stop.

Trademark and service mark registration in California is covered in MODEL STATE TRADEMARK LAW: BUSINESS AND PROFESSIONS CODE SECTION14200-14272.

A trade name is used to identify a company. A Trademark is used to identify its goods and to indicate a source and quality, even if that source is unknown.

You cannot actually register a trade name in the USPTO. It has to be a distinctive BRAND used on or in association with particular goods or services. TMEP 1202.01 "The Trademark Act does not provide for registration of trade names."

Do not rely upon answers of anyone who doesn't know you can register trademarks in each individual state, or several states, as well as the federal USPTO. Go look up the cited legal references and the Secretary of State's web pages and FAQ on it:

http://www.sos.ca.gov/business/ts/

It's a $70 fee (per class of goods or services) for 5 year registration.

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