Legal Question in Business Law in California

It would depend on who the plaintiff is, how they were harmed, and what the nature of the fraud is. A lot of fraudulent advertising is not something an individual can sue over in most cases. Much of it has to be referred to the authorities for action.

I agree. The statutory scheme favors enforcement by the Attorney General, District Attorneys, County Counsel and City Attorneys -- see, e.g., Business & Professions Code sections 17200 to 17206; also, B&P 17500. However, an ordinary individual who has suffered actual harm as a result of false or misleading advertising can sue based on ordinary fraud concepts.

Fraud filings are fraught with peril, and you may want to engage an attorney to help you. To the extent you are doing this on your own, please look to Cal. Civ. Code Section 1770 et seq. as well as Cal. Bus. & Prof. Code section 17200 and 17500. There may also be issues depending on the type of advertising (for example, email advertising is governed by Cal.Bus. & Prof. Code section 17529 et seq.)