Ten Words We Won’t Miss: FDA Publishes Final Rule Implementing Court Vacatur of LDT Rule

On September 19, 2025, FDA published in the Federal Register a final rule reverting the regulatory definition of “in vitro diagnostic products” (IVD products) in 21 C.F.R. § 809.3 to the text as it existed prior to the effective date of the May 2024 LDT Rule.

As we suspected when we blogged on the OIRA notice for this action, this new rule implements the March 31, 2025 Federal District Court decision vacating the LDT Rule, by removing the words “including when the manufacturer of these products is a laboratory,” which the LDT Rule added to the IVD products definition. In a footnote, the new rule notes that reverting the regulation’s text also changes the updated reference to the statutory definition of “device” from “section 201(h)(1)” back to “section 201(h),” which is less specific but still accurate.

Because the LDT Rule was already vacated by a Federal Court, FDA determined that this new rule is exempt from notice and comment rulemaking under 5 U.S.C. 553(b)(B), as it would be “impracticable, unnecessary, or contrary to the public interest” to follow such procedures.

The new rule provides an economic analysis of the impact of the LDT Rule not being in effect. Though it uses the primary estimates for the benefits and costs reported in the May 2024 LDT Rule, it adds that:

Portions of the broader benefit and cost uncertainty ranges overlap, thus indicating the possibility of negative net benefits of the Rule and positive net benefits of its no longer being in effect. Moreover, the quantitative estimates omit various regulatory consequences that are especially challenging to assess, such as any possible effect on innovation related to laboratory-developed tests (LDTs) associated with the Rule.

Plaintiffs argued in their case against the LDT Rule that FDA understated the costs associated with the rule by several orders of magnitude.  Although quite belated, it is nevertheless gratifying to see FDA acknowledge that its economic impact analysis did not adequately consider other critical factors such as the effect of the rule on innovation.

The new rule is signed by HHS Secretary Kennedy, which is unusual insofar as the FDA Commissioner almost always signs rules originating from FDA. It’s unclear what, if anything, this move is intended to signal, though it’s certainly consistent with this Administration’s general effort to centralize regulatory authority and decisionmaking and Secretary Kennedy’s specific penchant for directing FDA priorities, including its regulation of food and color additives and direct-to-consumer pharmaceutical advertising.