How to File a Trade Secret Misappropriation Lawsuit Under the Illinois Trade Secrets Act in Chicago
Illinois trade secret claims in Chicago are commonly filed under the Illinois Trade Secrets Act (765 ILCS 1065) and may also proceed in federal court under the Defend Trade Secrets Act. In Cook County and the Northern District of Illinois, the earliest missteps—poor trade secret identification and weak confidentiality proof—often decide the case. This article explains what qualifies as a trade secret, how to plead and prove misappropriation, where to file in Chicago, and what remedies you can seek.
Trade secret disputes in Chicago typically move fast because the harm—lost customers, diverted revenue, and irreversible disclosure—often happens before a business can react. The Illinois Trade Secrets Act (“ITSA”), 765 ILCS 1065, is the primary state-law vehicle for pursuing misappropriation, and many cases in the Chicago area are paired with a federal Defend Trade Secrets Act (“DTSA”) claim when interstate commerce is implicated. The practical goal in most cases is immediate injunctive relief, followed by a damages case built on clean proof of what the secret is, who took it, and how it was used.
1) What counts as a “trade secret” under the Illinois Trade Secrets Act
Under ITSA, a plaintiff must show the information at issue is a “trade secret” and that it was misappropriated. ITSA defines a trade secret broadly to include technical or non-technical information—such as formulas, patterns, compilations, programs, devices, methods, techniques, drawings, processes, financial data, and customer information—so long as two core requirements are met:
A. The information has independent economic value from not being generally known
The information must derive actual or potential economic value from being secret. In practice, Chicago courts look at whether competitors could gain a business advantage if they obtained it. Examples that frequently appear in ITSA cases include:
• Customer lists and relationships that are not readily ascertainable (e.g., a curated list reflecting years of relationship-building, decision-maker contacts, and buying history).
• Pricing models and margin data (discount structures, floor pricing, bid strategy).
• Source code or proprietary software logic and internal tooling.
• Manufacturing processes and quality-control methods.
B. The owner made “reasonable efforts” to maintain secrecy
ITSA does not require perfect security—reasonable efforts are enough. But this is where many plaintiffs lose leverage early. Common “reasonable efforts” evidence includes:
• Written confidentiality provisions (employment agreements, NDAs, contractor agreements).
• Access controls (role-based permissions, password protection, MFA, limited shared drives).
• Policies and training (confidentiality policies, onboarding/offboarding checklists).
• Marking and handling practices (confidential legends, restricted distribution, clean desk practices for sensitive materials).
In Chicago litigation, judges often focus on whether the alleged secret was broadly circulated internally or sent externally without restrictions. If your company treated the information casually, the defense will argue it was never a protectable trade secret.
2) What is “misappropriation” in an ITSA case
Misappropriation generally means the improper acquisition, disclosure, or use of a trade secret. ITSA covers both “taking” and “using,” and it can reach conduct by former employees, new employers, vendors, and competitors.
A. Misappropriation by improper acquisition
Improper acquisition can include theft, bribery, misrepresentation, breach of a duty to maintain secrecy, or espionage (including through electronic means). In a common Chicago scenario, an employee resigns, downloads a trove of files to a personal device or cloud folder, and then joins or forms a competing business.
B. Misappropriation by disclosure or use
Even if a defendant did not personally “steal” the information, using or disclosing it can be misappropriation if the defendant knew (or had reason to know) the information was obtained by improper means or under a duty of confidentiality. This matters when a competitor hires a team from a Chicago company and quickly begins targeting the same customers with eerily similar pricing or proposals.
3) Pre-suit triage: what to do before filing in Chicago
Because emergency relief may be necessary, pre-suit steps should be organized for speed and credibility. Before filing, counsel will typically help you do four things:
A. Identify the trade secrets with specificity (without over-disclosing)
You must describe the trade secrets well enough to put the defendant on notice and to allow the court to assess protectability. Vague labels (“confidential business information”) are not enough. At the same time, you should avoid publicly filing the secret itself. Chicago courts often manage this tension through protective orders, sealed exhibits, and carefully drafted descriptions (e.g., categories plus exemplars).
B. Preserve and collect evidence
Trade secret cases are evidence-heavy and forensics-driven. Key sources include:
• Device and network logs showing downloads, USB use, printing, external drives, and unusual access.
• Email and messaging (forwarding to personal accounts, Slack/Teams exports, texts where permitted and preserved).
• Cloud activity (Google Drive, Dropbox, iCloud, OneDrive).
• Exit interview records and signed acknowledgments of return of property.
• Competitive timing evidence (new employer’s sudden pitch deck, same customer targets, similar pricing).
C. Send a litigation hold and consider a demand letter
A litigation hold preserves your evidence and can be paired with a notice to the departing employee and the new company to preserve theirs. In some cases, a targeted demand letter can recover devices, secure written certifications, and avoid a public lawsuit. In others, it tips off the defendant and increases the risk of spoliation or continued use—so timing is strategic.
D. Evaluate restrictive covenants separately
Non-compete and non-solicitation agreements are not required for an ITSA claim, but they can support injunctive relief and show the defendant understood confidentiality obligations. Illinois restrictive covenant law is its own landscape; don’t assume a non-compete automatically solves a trade secret problem.
4) Where to file: Cook County Circuit Court vs. Northern District of Illinois
In Chicago, trade secret lawsuits are commonly filed either in the Circuit Court of Cook County (state court) or the U.S. District Court for the Northern District of Illinois (federal court). The “right” forum depends on facts, parties, desired speed, and whether federal jurisdiction exists.
A. Cook County Circuit Court (state court)
State court is often chosen when the parties are Illinois-based and the claims are primarily under ITSA. State court can move quickly on emergency injunction requests, and local practice experience matters.
B. Northern District of Illinois (federal court)
Federal court may be available via diversity jurisdiction (parties from different states with amount in controversy met) or federal question jurisdiction if you bring a DTSA claim alongside ITSA. DTSA requires the trade secret be related to a product or service used in, or intended for use in, interstate or foreign commerce—a standard many Chicago businesses can satisfy.
C. Removal risk and strategy
Even if you file in Cook County, defendants may remove to federal court if federal jurisdiction exists. A Chicago filing strategy should anticipate removal and be drafted with both forums in mind—especially for injunction briefing and protective-order needs.
5) How to draft the complaint: core ITSA elements and practical pleading tips
A strong ITSA complaint does more than recite statutory words. It tells a provable story supported by documents and a clean timeline.
A. Allegations to include
1) The trade secret(s): Describe the information with enough detail to distinguish it from general knowledge and public data (e.g., “a compilation of customer contacts including decision-maker identities, contract renewal dates, pricing history, and product specifications maintained in [system name]”).
2) Secrecy measures: Identify the reasonable efforts—NDAs, restricted access, policies, audit logs, and limited distribution.
3) Ownership and value: Explain how the secret provides a competitive advantage (e.g., higher win rates, reduced bidding time, higher margins).
4) Misappropriation facts: Lay out who accessed what, when, by what means, and how the defendant used it (soliciting the same customers, mirroring pricing, launching a competing product).
5) Harm and threat of ongoing harm: Connect the misconduct to lost business, threatened disclosure, and why money damages may be inadequate without an injunction.
B. Avoid common pleading mistakes
• Overbreadth: Claiming “everything the company knows” invites dismissal or narrowing.
• Under-identification: Being too vague undermines emergency relief and discovery.
• Public filing of secrets: Use motions to seal or file sensitive exhibits under protective order procedures where appropriate.
6) Emergency relief in Chicago: TROs and preliminary injunctions
Many ITSA cases turn on whether the plaintiff can obtain an early court order to stop use or disclosure. Courts may issue:
A. Temporary Restraining Order (TRO)
A TRO is short-term emergency relief, sometimes requested on an expedited basis. To succeed, you generally need strong evidence of imminent harm and a clear showing of likely success on the merits. In practice, persuasive TRO papers often include forensic declarations, screenshots, access logs, and customer-impact evidence.
B. Preliminary injunction
A preliminary injunction can last through the case. Remedies may include prohibiting use/disclosure, ordering return or deletion of data, requiring device imaging, restricting competitive activities tied to the secret, and allowing expedited discovery.
C. Protective orders and “attorneys’ eyes only”
Trade secret litigation requires confidentiality inside the litigation itself. Chicago courts commonly enter protective orders to limit how confidential materials are used, who
