Can a Former Employer Stop You From Working for a Competitor Because You Know Its Trade Secrets?

Last updated: November 2026. Reviewed by Pavel Kolmogorov, California business litigation attorney (State Bar No. 321018).

No, not on that argument alone. California rejects the inevitable disclosure doctrine, the theory that someone who knows a former employer's trade secrets will unavoidably use them in a similar job. A California court may enjoin actual or threatened misappropriation, and a threat has to be shown with evidence such as files taken or past misuse. What you carry in your head is not enough. Kolmogorov Law, P.C. represents employees, hiring companies, and former employers in these disputes in Orange County, Los Angeles, and statewide.

Call (909) 235-6116 or contact us online to discuss an inevitable disclosure threat, or a departing employee who knows your company's secrets.

What the inevitable disclosure doctrine is

In some states, an employer can ask a court to keep a former employee out of a competing job without proving that anything was taken. The argument runs in three steps. The employee knows our pricing, our roadmap, and our formulas. The new job is so similar that it cannot be done without drawing on that knowledge. Disclosure is therefore inevitable. The order that follows restricts the employment itself.

California does not accept that reasoning. The Court of Appeal rejected the doctrine outright, holding that it creates an after-the-fact covenant not to compete and restricts employee mobility. (Whyte v. Schlage Lock Co. (2002) 101 Cal.App.4th 1443.)

The rule rests on a statute. Every contract that restrains a person from engaging in a lawful profession, trade, or business is void to that extent, subject to exceptions listed in the same chapter. (Bus. & Prof. Code, § 16600, subd. (a).) An injunction built on inevitable disclosure would hand the employer a non-compete it never had, or could not lawfully have. Our non-compete page covers that statute.

What a former employer must prove instead

The trade secret statute lets a court enjoin actual or threatened misappropriation. (Civ. Code, § 3426.2, subd. (a).) Rejecting inevitable disclosure did not delete the word "threatened." It means the threat must be proved.

A later Court of Appeal decision confirmed that a threat may be enjoined, and held that it takes more than possession of trade secrets by someone who acquired them by proper means. (Central Valley General Hospital v. Smith (2008) 162 Cal.App.4th 501.) The court described what a real threat can look like. The person still holds the secrets and has misused or disclosed some of them before. Or the person holds them and intends to use or disclose them improperly. An employee who learned the secrets by doing the job usually acquired them properly.

So nearly every one of these disputes turns on one question. What did the person do, apart from accepting a new job?

Conduct that tends to support an injunction: files forwarded to a personal account, a cloud sync in the final week, a laptop returned wiped. Facts that do not: the similarity of the two jobs, seniority, or a claim that the employee "knows everything."

If you are the employee, or the company that hired one

A letter that leans on inevitable disclosure often means the sender has no proof of taking. It still deserves a careful answer.

Consider a regional sales director who leaves a packaging supplier for a rival. She returns her laptop, keeps no files, and signs the new company's instruction not to use prior-employer information. The old employer writes that her knowledge of its pricing makes disclosure inevitable and demands that she be benched for a year. On those facts, California law gives the demand little support.

The response should be factual and prompt. Do not delete anything. Confirm in writing what was returned. Our page on being accused of taking company data walks through the reply.

The law also gives the employee some weight to push back. An employer that attempts to enforce a void restraint commits a civil violation. The employee may sue for an injunction or actual damages and, if she prevails, recover attorney's fees. (Bus. & Prof. Code, § 16600.5, subds. (d), (e).) A trade secret claim filed in bad faith can also end in a fee award, as our page on bad faith trade secret claims explains.

If you are the former employer

You have remedies. They depend on evidence, so start there.

Order a targeted forensic review in the days after the resignation. If it shows taking, the case changes. A process engineer who emails herself batch records the week before joining a competitor has not handed you an inevitable disclosure case. She may have handed you a threatened misappropriation case with evidence behind it, and a court can act on that quickly. Our TRO and preliminary injunction page explains the timing.

A court may also compel affirmative acts to protect a trade secret, such as the return of files. (Civ. Code, § 3426.2, subd. (c).)

What I advise against is the letter that demands a competitor fire or sideline a new hire because of what the person knows. It rarely works in California, and it can create exposure for the sender.

What an injunction can and cannot cover

Even where taking is proved, the order is aimed at the information: do not use it, do not disclose it, return it. The job is usually left alone.

An injunction under the federal Defend Trade Secrets Act may not prevent a person from entering into an employment relationship. Any conditions placed on that employment must rest on evidence of threatened misappropriation, and not merely on what the person knows. (18 U.S.C. § 1836(b)(3)(A)(i).) The same provision bars an order that conflicts with a state law prohibiting restraints on a lawful profession, so filing in federal court does not get an employer around California's rule. Our comparison of the federal and California statutes has more.

Out-of-state agreements and California employees

Many of these threats come from an employer based elsewhere, holding a non-compete and a forum clause from another state. A contract that is void under California's restraint-of-trade chapter is unenforceable regardless of where and when it was signed. (Bus. & Prof. Code, § 16600.5, subd. (a).)

A second statute protects employees who primarily reside and work in California, under contracts entered into, modified, or extended on or after January 1, 2017. As a condition of employment, they generally cannot be required to litigate California claims in another state or to give up the protection of California law. Such a clause is voidable by the employee, unless the employee was individually represented by counsel in negotiating it. (Lab. Code, § 925, subds. (a), (b), (e), (f).)

Whether a court in another state will defer to California is a harder question, and where the first case is filed can matter a great deal.

What to bring to the first meeting

Bring every agreement signed with the former employer, including confidentiality, non-compete, and forum clauses. Add the demand letter, the new job description, and a list of what was returned and when. Employers should bring any forensic findings.

Frequently asked questions

My old company says I will inevitably use its trade secrets at my new job and is threatening an injunction. Can it do that in California?

Not on that theory. California courts reject the inevitable disclosure doctrine because it operates as a non-compete imposed after the fact. Your former employer would need evidence of actual or threatened misappropriation, such as files you took or misuse that has already occurred. Knowing confidential information, and taking a similar job, does not meet that standard.

We hired a salesperson from a competitor and received a letter demanding that we fire her. Do we have to comply?

Usually not. In California, a competitor cannot block a hire simply because the employee knows its confidential information. Take the letter seriously anyway. Confirm that she brought nothing with her, preserve records, and respond with facts. If files were taken, the analysis changes.

Does California recognize the inevitable disclosure doctrine?

No. The California Court of Appeal rejected it in 2002, reasoning that it creates a covenant not to compete after the fact and conflicts with Business and Professions Code section 16600. An employer must prove actual or threatened misappropriation under the Uniform Trade Secrets Act. Similarity between the old job and the new one is not proof.

What is threatened misappropriation in California?

It is a showing, based on conduct, that a trade secret is in danger of being misused. A California appellate court has described a threat as a defendant who still holds trade secrets and has misused some before, or who intends to use or disclose them improperly. Mere possession of information acquired properly on the job is not a threat that supports an injunction.

Can an out-of-state non-compete be enforced against a California employee?

Generally no. Under Business and Professions Code section 16600.5, a contract void under California's restraint-of-trade rules is unenforceable regardless of where and when it was signed, and an employer that attempts to enforce one commits a civil violation. A court in another state may see the question differently, so early advice matters.

Talk to a California trade secret attorney

Call (909) 235-6116 or contact us online. Kolmogorov Law, P.C. is located at 327 Magnet, Irvine, CA 92618, and represents employers, employees, and hiring companies in Orange County, Los Angeles, and throughout California.

This page provides general information about California and federal law and is not legal advice. Outcomes depend on the agreements, the evidence of what was taken or used, and the court.