September 19, 2025

On September 19, 2025, the FDA elected to amend the wording of its LDT Final Rule that would have reclassified laboratory-developed tests (LDTs) as medical devices. Last week, RFK Jr. issued an entry into the Federal Register titled Medical Devices; Laboratory Developed Tests; Implementation of Vacatur, stating that the FDA was removing the words “including when the manufacturer of these products is a laboratory” from the Final Rule, effectively reverting to the text of the regulation as it existed before the Final Rule’s effective date. This move follows a March 31, 2025, decision by the U.S. District Court for the Eastern District of Texas to vacate the 2024 rule in its entirety.

What this means in practice:

• The amendment to FDA’s device definition in 21 C.F.R. § 809.3, which expanded “in vitro diagnostic products (IVDs)” to cover tests manufactured by laboratories, will be rolled back, restoring the prior definition that existed before the 2024 Rule.
• All compliance deadlines and enforcement stages for LDTs under the vacated rule are no longer legally binding.
• Laboratories previously preparing for compliance will no longer be required to build or modify operations to satisfy device requirements under this rule.
• Oversight of LDTs returns (for now) primarily to CMS under the Clinical Laboratory Improvement Amendments (CLIA) regime.

Stakeholders such as clinical labs, hospitals, and diagnostic developers have largely welcomed the rollback, pointing to concerns over cost, access, and regulatory burdens.

In May 2024, the U.S. Food and Drug Administration issued its long-anticipated Final Rule on Laboratory-Developed Tests (LDTs), formally titled “Medical Devices; Laboratory-Developed Tests.” This rule marked the agency’s most significant effort to extend its regulatory authority over LDTs, seeking to classify them as in vitro diagnostic medical devices under the Federal Food, Drug, and Cosmetic Act (FD&C Act). The Final Rule aimed to phase out decades of FDA’s general enforcement discretion toward LDTs and replace it with a structured regulatory framework. By doing so, FDA intended to impose requirements such as premarket review, registration, quality system compliance, and post-market reporting on clinical laboratories offering LDTs.

What the Rule Proposed

• The 2024 Final Rule titled “Medical Devices; Laboratory-Developed Tests (LDTs)” ended FDA’s longstanding policy of general enforcement discretion toward LDTs.
• It redefined “in vitro diagnostic product”, which is classified as a medical device, to explicitly include tests “when the manufacturer … is a laboratory,” effectively treating LDTs as devices for regulatory purposes.
• It set a phased four-year timeline for enforcement, requiring compliance with device-related requirements such as premarket review, quality systems, labeling, and post-market reporting.

Why It Was Controversial

• Statutory authority: Critics argued the FD&C Act does not authorize FDA to regulate LDTs comprehensively, since Congress already provided oversight under CLIA.
• Cost burdens: Labs warned of high compliance costs, especially for smaller hospitals and academic labs.
• Access & innovation concerns: Opponents feared reduced access to specialized diagnostics and slower innovation.
• Implementation challenges: Many questioned how FDA would draw the line between kits and services, and how labs could realistically adapt.

Following FDA’s issuing of the Final Rule, a number of industry stakeholders who opposed the LDT final rule took their arguments to court. The plaintiffs, including clinical laboratory associations, professional pathology groups, individual labs, and physicians, argued that the Rule exceeded FDA’s authority. In a landmark decision on March 31, 2025, Judge Sean D. Jordan with the U.S. District Court for the Eastern District of Texas granted summary judgment in favor of the plaintiffs in the consolidated cases American Clinical Laboratory Association (ACLA) v. FDA and Association for Molecular Pathology (AMP) v. FDA. This ruling vacated the Final Rule in its entirety and referred it back to the US Department of Health and Human Services (HHS) for further consideration.

By formally rescinding the 2024 Final Rule, FDA has acknowledged the limits of its regulatory reach following the Texas court’s decision. For laboratories, hospitals, and diagnostic developers, this brings immediate clarity: LDTs are not subject to FDA’s device framework and remain regulated under CLIA. In practical terms, labs are no longer facing the looming compliance deadlines or costly transitions that the Final Rule would have required.

However, the long-standing debate about LDT oversight is far from resolved. Stakeholders should anticipate that Congress may revisit the issue, particularly given concerns about test quality, patient safety, and innovation. Until such legislative action is taken, laboratories can continue their work under the existing CLIA framework, but they should remain vigilant to future proposals that could re-ignite the debate over how, and by whom, LDTs are regulated.