Sixth Circuit Rejects Heightened Evidentiary Standard For Preliminary Injunctions In Trade Secret Cases: PCC Airfoils, LLC v. Daugherty

Federal district courts in the Sixth Circuit have spent years applying a heightened evidentiary burden to preliminary injunction motions in trade secret cases, requiring movants to prove every factor by clear and convincing evidence. On May 19, 2026, the Sixth Circuit put a stop to it. In PCC Airfoils, LLC v. Daugherty, the court reversed a denial of preliminary relief and held that the four preliminary injunction factors are equitable considerations to be balanced, not elements each requiring heightened proof.

For employers trying to protect trade secrets after a longtime employee leaves for a competitor, the distinction matters. Preliminary injunctions are won and lost on the proof a plaintiff can muster in the first weeks of a case, before discovery, before forensic experts have finished their work, and often before the full extent of what was taken is even known. Raising the evidentiary floor for every factor put effective trade secret protection out of reach in many cases. The Sixth Circuit has now closed that gap.

How the Case Arose

Justin Daugherty worked at PCC Airfoils, an Ohio manufacturer of industrial gas turbine airfoils, for 26 years. He had risen to director of engineering before a corporate restructuring stripped him of the title, and he grew frustrated with the lack of further opportunity. When Consolidated Precision Products, one of PCC’s competitors, offered him a director of engineering role, he took it. Daugherty did not have a non-compete with PCC.

In his last two days on the job, Daugherty queued four documents containing confidential information about PCC’s airfoils for printing. Forensic analysts could not confirm whether the documents printed, and PCC could not find those documents in the materials Daugherty left behind. PCC concluded that Daugherty had walked out with its trade secrets. It sued under the federal Defend Trade Secrets Act and the Ohio Uniform Trade Secrets Act, added a contractual confidentiality claim, and moved for a preliminary injunction barring him from disclosing the information or working on competing airfoil projects.

The district court denied the motion. It concluded that PCC had not proved each of the four preliminary injunction factors by clear and convincing evidence. PCC appealed.

What the Sixth Circuit Held

Writing for a unanimous panel, Chief Judge Sutton confirmed what trade secret practitioners have long argued. The four familiar preliminary injunction factors, likelihood of success on the merits, irreparable harm, the balance of equities, and the public interest, operate as a sliding scale. A strong showing on one factor can offset a weaker showing on another, and no factor requires proof by clear and convincing evidence.

The court traced its analysis to Winter v. Natural Resources Defense Council. What Winter requires is a “clear showing” that, on balance, the equities favor relief. The district court had read “clear showing” as “clear and convincing evidence” and applied it to each factor individually. That reading, the Sixth Circuit explained, is wrong. The Supreme Court reserves the clear and convincing standard for a narrow category of civil cases involving certain statutes, constitutional rights, or unusually coercive government action. A private commercial preliminary injunction motion is not on the list.

Two limits remain. A plaintiff still has to show some likelihood of success on the merits and some risk of irreparable harm. Without both, there is nothing to balance and the motion fails. The court was emphatic on that point.

The court also addressed a procedural question that recurs in dual-statute trade secret cases. When the plaintiff brings claims under both federal and state law in federal court, the preliminary injunction analysis is governed by federal procedural rules. State appellate decisions reading clear and convincing evidence into each factor of the state-law standard do not control in federal court, even where the underlying state-law claim does.

The court reversed and remanded for the district court to apply the corrected standard.

Why This Matters

The preliminary injunction is the most important moment in most trade secret cases. By the time discovery closes, the information is already in a competitor’s hands, the competitive use has occurred, and the damage is done. The plaintiff who cannot get into court quickly, with a real prospect of an injunction, is often the plaintiff who loses, regardless of how strong the underlying claim turns out to be.

Requiring clear and convincing evidence on every factor at the outset of a case set a threshold that trade-secret plaintiffs typically could not clear. The proof needed to show what was taken, how it was used, and what irreparable harm will follow takes time and discovery, none of which a plaintiff has when filing the motion. The Sixth Circuit’s decision corrects that mismatch.

Defendants in this circuit will need to oppose preliminary injunction motions on their merits going forward, rather than relying on a heightened standard to do the work.

What Employers Should Do Now

A preliminary injunction record is built long before a complaint is filed. The decision rewards employers who prepare.

• Audit trade secret hygiene. Identify the information that actually qualifies as a trade secret. Label it. Restrict access. Track who handles it. The “reasonable measures” requirement of the DTSA is increasingly outcome-determinative, and a thin record on that point can sink the likelihood-of-success factor regardless of the rest of the case.
• Tighten exit procedures. Most trade secret cases begin with a USB drive, a print queue, or a forward to a personal email account in an employee’s last days. Offboarding should include forensic preservation of company devices and accounts, a review of email and printing activity in the preceding weeks, and an exit interview that documents what the employee acknowledges and what was returned.
• Develop the irreparable harm story early. Boilerplate affidavits about generalized competitive risk no longer carry the weight they once might have. Counsel should be ready to explain, with specificity, what the information is, why disclosure causes harm that money damages cannot cure, and why intervention is needed now.
• Move quickly. Sixth Circuit law continues to treat delay as evidence that the alleged harm is not, in fact, irreparable. PCC Airfoils lowers the proof threshold, not the urgency. A motion filed within days or weeks of discovering the conduct will land very differently than one filed months later.
• Use layered contractual protections. Confidentiality agreements, narrowly drawn non-solicits, and intellectual property assignments together build the contractual record that supports the likelihood-of-success factor. PCC Airfoils itself shows that the absence of a non-compete does not foreclose preliminary relief when the rest of the program is sound.

Bottom Line

PCC Airfoils is the second Sixth Circuit decision in 2026, following Fetch! Pet Care, Inc. v. Atomic Pawz Inc., to align preliminary injunction practice in this circuit with the equitable approach the Supreme Court has long applied. Together they close a doctrinal gap that has cost trade secret plaintiffs in this circuit real cases. Federal courts here will now be more willing to grant preliminary relief where the equities clearly favor it, even on the partial record available at the outset.

Likelihood of success and irreparable harm remain the floor. The rest of the inquiry now turns on weighing, not on heightened proof.

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