How long do I have to sue for trade secret theft in California?

Three years from when the misappropriation was discovered or reasonably should have been discovered, under California's Uniform Trade Secrets Act (Civil Code section 3426.6). A continuing misappropriation counts as a single claim, so the clock runs from the first discovery, not from each later use. The federal Defend Trade Secrets Act also allows three years.

Civil Code section 3426.6 gives trade secret claims three years from actual or constructive discovery, and treats a continuing misappropriation as one claim, so waiting while a departed employee keeps using the information does not restart anything. The claim itself requires proof that the information derives independent economic value from not being generally known and was subject to reasonable secrecy efforts (section 3426.1): confidentiality agreements, access restrictions, marking. Without those efforts there is no secret to protect. Remedies include injunctions (section 3426.2), damages measured by loss, unjust enrichment, or a reasonable royalty (section 3426.3), and, for willful and malicious misappropriation, exemplary damages up to double plus attorney fees (section 3426.4). Procedure adds a gate: Code of Civil Procedure section 2019.210 requires the plaintiff to identify the claimed secrets with reasonable particularity before taking discovery on them. The federal Defend Trade Secrets Act (18 U.S.C. § 1836) opens federal court on the same three-year period. Investigate departures promptly; accrual starts at suspicion, not certainty.

Authority: Cal. Civ. Code § 3426.6