Illinois
Illinois Trade Secret Laws: UTSA, Remedies & Deadlines
Illinois protects confidential business information under the Illinois Trade Secrets Act (ITSA), 765 ILCS 1065/1 to 1065/9, enacted in 1987. The ITSA departs from the standard UTSA limitations period: plaintiffs have five years from discovery to bring a misappropriation claim (765 ILCS 1065/7), and the statute expressly recognizes customer and potential-customer lists as protectable trade secrets.
This guide is part of our Trade Secret Laws by State series.
Information last verified on 2026-06-25. This article presents general legal information, not legal advice. For guidance on a specific situation involving Illinois trade secret law, consult a lawyer licensed in Illinois. See also our Trade Secret Laws by State hub for additional state guides.
Does Illinois have a trade secret law?
Illinois enacted the Illinois Trade Secrets Act in 1987, codified at 765 ILCS 1065/1 to 1065/9. The ITSA is modeled on the Uniform Trade Secrets Act but contains several notable features, including an extended five-year limitations period and an express statutory recognition of customer and potential-customer lists as qualifying trade secrets. Under 765 ILCS 1065/8, the ITSA preempts conflicting tort, restitution, and other civil claims based on misappropriation of a trade secret, but does not affect criminal law, contract claims, or other non-misappropriation civil claims. Illinois courts have developed a substantial body of case law interpreting the ITSA, particularly in employment-related trade secret disputes.
What counts as a trade secret and misappropriation in Illinois?
Under 765 ILCS 1065/2(d), a trade secret is information, including but not limited to technical or non-technical data, a formula, pattern, compilation, program, device, method, technique, drawing, process, financial data, or list of actual or potential customers or suppliers, that:
- Is sufficiently secret to derive economic value, actual or potential, from not being generally known to other persons who can obtain economic value from its disclosure or use; and
- Is the subject of efforts that are reasonable under the circumstances to maintain its secrecy or confidentiality.
The explicit inclusion of lists of actual or potential customers and suppliers is a notable ITSA provision. Illinois courts have applied this provision to protect client databases, prospecting lists, and similar business development materials, provided the owner takes reasonable measures to keep them confidential. Generic or publicly available customer information is less likely to qualify.
Under 765 ILCS 1065/2(b), misappropriation means acquisition of a trade secret by improper means, or disclosure or use without consent by a person who obtained the secret through improper means, breach of a duty to maintain secrecy, or through a third party with knowledge of such circumstances. Improper means under 765 ILCS 1065/2(a) include theft, bribery, misrepresentation, breach of a duty to maintain secrecy, and espionage. Reverse engineering and independent development are lawful under 765 ILCS 1065/2(a).
Remedies and the limitations period in Illinois
Illinois offers the following remedies under the ITSA:
- Injunction: Under 765 ILCS 1065/3, courts may enjoin actual or threatened misappropriation. An injunction may condition future use on payment of a reasonable royalty when an absolute prohibition would be inequitable.
- Damages: Under 765 ILCS 1065/4, a plaintiff may recover actual loss caused by misappropriation plus unjust enrichment not captured by actual loss. Where neither measure is provable, courts may award a reasonable royalty for the period of unauthorized use.
- Exemplary damages: Willful and malicious misappropriation supports an award of up to twice the compensatory damages (765 ILCS 1065/4).
- Attorney fees: Available when a claim of misappropriation is made or defended in bad faith, or when willful and malicious misappropriation is proven (765 ILCS 1065/5).
The limitations period in Illinois is five years from the date the misappropriation was discovered or, through reasonable diligence, should have been discovered (765 ILCS 1065/7). This is a material deviation from the three-year standard in the UTSA and in many other states. The longer period gives Illinois plaintiffs more time to identify and respond to misappropriation, which can be difficult to detect when it involves gradual competitive harm.
How the federal DTSA applies in Illinois
The Defend Trade Secrets Act, 18 U.S.C. §§ 1836-1839, has provided a federal civil remedy since May 2016 for misappropriation of trade secrets that relate to interstate or foreign commerce. The DTSA does not preempt Illinois law (18 U.S.C. § 1838), and Illinois plaintiffs routinely plead both statutes in a single action to access federal jurisdiction while preserving state remedies.
Key DTSA considerations for Illinois businesses include:
- A three-year federal limitations period from discovery (18 U.S.C. § 1836(d)), which is two years shorter than the Illinois state period. Choosing where to file can affect the available window.
- Ex parte seizure to prevent propagation of the secret, available in extraordinary circumstances (§ 1836(b)(2)).
- Exemplary damages up to twice and attorney fees for willful and malicious misappropriation, parallel to Illinois ITSA remedies.
- Whistleblower immunity: the DTSA immunizes individuals who disclose trade secrets to government officials or attorneys in connection with a suspected legal violation (§ 1833(b)(1)). Employers must include a notice of this immunity in confidentiality or non-disclosure agreements signed or updated after May 11, 2016 (§ 1833(b)(3)). Omitting the notice forfeits the right to claim exemplary damages and attorney fees under the DTSA.
Federal criminal exposure for trade secret theft may also arise under the Economic Espionage Act, 18 U.S.C. §§ 1831-1832.
This article provides general legal information about Illinois trade secret law as of 2026-06-25. It is not legal advice. Laws can change; consult a lawyer licensed in Illinois before taking action based on this information.
Related articles
- Trade Secret Laws by State
- Idaho Trade Secret Laws
- Indiana Trade Secret Laws
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Last updated: 2026-06-25.
Frequently Asked Questions
What qualifies as a trade secret under Illinois law?
Under 765 ILCS 1065/2(d), a trade secret is information that derives economic value from not being generally known or readily ascertainable by those who could profit from it, and that the owner protects through reasonable confidentiality measures. The Illinois statute expressly includes lists of actual or potential customers and suppliers, making it easier than in some states to protect client databases and prospect lists when reasonable precautions are in place.
How long do I have to sue for trade secret misappropriation in Illinois?
Illinois provides five years from the date the misappropriation was discovered or, through reasonable diligence, should have been discovered (765 ILCS 1065/7). This is longer than the three-year UTSA baseline used by most states. Note that a parallel DTSA federal claim carries only a three-year limitations period, so the choice of forum can affect how much time you have.
What damages are available in an Illinois trade secret case?
A prevailing plaintiff may recover actual loss plus unjust enrichment, or a reasonable royalty if neither measure is quantifiable. Willful and malicious misappropriation can yield exemplary damages up to twice the compensatory award. Attorney fees are available when misappropriation is willful and malicious or when a claim or defense is brought in bad faith. Courts may also issue injunctions to stop threatened or ongoing misappropriation.
Are customer lists protected as trade secrets under Illinois law?
Yes, explicitly. The ITSA, 765 ILCS 1065/2(d), lists actual or potential customers and suppliers among the categories of qualifying trade secrets. To obtain this protection, the business must show that the lists derive economic value from their secrecy and that the business takes reasonable steps to keep them confidential. Generic or publicly sourced contact information is unlikely to qualify.
Should I plead both the Illinois Trade Secrets Act and the federal DTSA?
In most cases, yes. Pleading both maximizes your forum options and remedies. The DTSA provides access to federal court and additional tools such as ex parte seizure. The ITSA's five-year limitations period can be advantageous for claims first discovered more than three years ago. Because the DTSA does not preempt Illinois law, there is generally no reason to choose one over the other. Consult Illinois counsel to evaluate the best strategy for your situation.
Sources and References
- Illinois Trade Secrets Act, 765 ILCS 1065/1 to 1065/9(ilga.gov).gov
- Defend Trade Secrets Act, 18 U.S.C. §§ 1836-1839(law.cornell.edu)
- Uniform Trade Secrets Act (Uniform Law Commission)(uniformlaws.org)
- Economic Espionage Act, 18 U.S.C. §§ 1831-1832(law.cornell.edu)