California Labor Code Section 2870 stops your employer from claiming inventions you create entirely on your own time, with your own resources, using no trade secrets, and unrelated to the company’s business or planned research. Any contract clause that tries to reach further than that is unenforceable in California.1California Legislative Information. California Code Labor Code 2870 – Inventions Made by an Employee
The statute matters because nearly every California tech company, research organization, and engineering firm asks new hires to sign an invention assignment agreement. Those agreements are legal, but Section 2870 sets the outer limit of what an employer can take.
The Four Conditions Your Invention Must Meet
Section 2870 protects your invention from an assignment clause only when all four conditions are satisfied:
- You developed it entirely outside working hours.
- You used none of your employer’s equipment, supplies, or facilities.
- You did not rely on your employer’s confidential or trade secret information.
- The invention does not relate to your employer’s current business or to research and development the company is actively pursuing or has concrete plans to pursue.
Every one of these matters. Writing a few lines of code for a side project on your company laptop can undermine the ownership claim. So can drawing on proprietary data you learned on the job, even when the invention itself looks unrelated.2California Legislative Information. California Code LAB 2870 – Inventions Made by an Employee
When the Employer Can Still Claim Your Invention
Two situations let the employer enforce an assignment clause even if you worked on your own time:
- The invention relates to the employer’s business, meaning what the company does now or research and development it is demonstrably planning. Vague corporate ambitions don’t count. A documented R&D roadmap does.
- The invention results from work you performed for the employer. If your job duties led you to the invention, finishing it at home on a Saturday doesn’t change the answer.
The “relates to the employer’s business” test is where most disputes land. A software engineer at a cybersecurity company who invents a new encryption method on weekends faces a much harder ownership argument than one who invents a kitchen gadget. The closer your invention sits to your employer’s field, the weaker your claim.1California Legislative Information. California Code Labor Code 2870 – Inventions Made by an Employee
Written Notice Your Employer Owes You
Section 2872 requires more than just contract language. If your employment agreement contains any provision requiring you to assign invention rights, the employer must give you written notice, at the time you sign, telling you the clause does not apply to inventions that qualify under Section 2870.3California Legislative Information. California Code Labor Code 2872
The notice requirement applies to any employment agreement entered into after January 1, 1980. Most California employers satisfy it by attaching the text of Section 2870 as an exhibit to the assignment agreement. A missing notice doesn’t automatically void the assignment clause, but it strengthens your position in any later dispute.
Section 2871 adds a companion protection: your employer cannot require you to agree to an assignment provision that Section 2870 makes unenforceable. Hiring and continued employment can’t be conditioned on signing away rights the statute reserves to you.
Who Has to Prove What
This part catches many employees off guard. If a dispute arises, the burden of proof sits with you. You have to show that your invention qualifies for Section 2870’s protection.3California Legislative Information. California Code Labor Code 2872
That means evidence of when you worked on the invention, what resources you used, and why it sits outside your employer’s business. Memory two years after the fact will not carry you. In Cubic Corp. v. Marty, the California Court of Appeal confirmed that provisions violating Section 2870 are void and unenforceable to that extent, while the employee still bears the burden of showing the invention qualifies.4Justia. Cubic Corp. v. Marty (1986)
How Section 2870 Interacts With Your Assignment Agreement
An invention assignment clause that reaches inventions meeting all four conditions is void to that extent. Courts do not throw out the whole agreement. They refuse to enforce the overreaching portion. Section 2870(b) declares such provisions “against the public policy of this state and unenforceable.”1California Legislative Information. California Code Labor Code 2870 – Inventions Made by an Employee
Most well-drafted agreements include a “prior inventions” exhibit. It’s a form where you list inventions you created before joining the company that you want excluded from the assignment. Fill it out carefully. Leaving it blank creates a presumption that nothing existed beforehand, which can complicate any later claim that a project predated your hire.
Disclosure Is a Separate Obligation
Even when you believe an invention is fully yours under Section 2870, your contract may still require you to disclose it so the company can evaluate whether the assignment clause applies. Failing to disclose can create legal problems even if the invention would ultimately have been found to be yours. The disclosure requirement and the assignment requirement are two different things. Read your specific agreement before assuming silence is safe. If you do disclose, put it in writing and clearly state your position that the invention qualifies under Section 2870. That record protects you later.
Section 2870 Does Not Cover Independent Contractors
The statute applies only to employees. If you work as an independent contractor, these protections don’t reach you. Invention rights are governed entirely by your contract with the hiring company and by federal patent law defaults.
This distinction matters in California, where misclassification disputes are common. If you’re classified as a contractor but function as an employee, Section 2870 could apply, but you would first have to establish the misclassification, and the stakes in that fight run well beyond invention rights.
Practical Steps to Protect Ownership
Because the burden falls on you, documentation carries the case. What actually holds up:
- Keep a dated log. Record when you worked on the invention, where, and what equipment you used. Handwritten notebooks with dated entries carry weight, and timestamped electronic records work too.
- Use only personal resources. Your own computer, your own internet connection, your own space. Never use your employer’s email, cloud storage, code repositories, or lab equipment for a personal project.
- Stay away from your employer’s field. If your day job involves machine learning and your side project also involves machine learning, you face an uphill fight regardless of how clean your documentation is.
- Read your employment agreement. Know exactly what the assignment clause, the disclosure requirement, and the prior inventions exhibit say before you start building.
- Disclose in writing when your agreement requires it, and state your Section 2870 position on the same document.
A consultation with an intellectual property attorney before you put serious time into a side invention is almost always worth the cost. The line between “relates to the employer’s business” and “unrelated” is often blurrier than it looks from where you sit.