Can you stop a departing California employee from joining a competitor? Generally, no—even if the employee signed a noncompete agreement.
California prioritizes employee mobility and open competition. Business and Professions Code §§ 16600 and 16600.1 generally make employment noncompetes void and prohibit employers from requiring them. Limiting the restriction to six months or a small geographic area does not cure the problem.
The principal exception: a qualifying sale of a business or ownership interest. Under § 16601, a seller may agree to geographic restrictions on competition that protect the goodwill the buyer purchased. Narrow exceptions also apply to certain partnership and LLC departures or dissolutions.
For employers, the takeaway is simple: an employee’s signature does not make an otherwise unlawful noncompete enforceable.