In March 2025, a federal district court issued a landmark ruling that reaffirmed a critical distinction in healthcare regulation: clinical laboratory services are not medical devices. The ruling struck down the FDA’s attempt to expand its authority over lab-developed tests (LDTs), finding the agency had no statutory basis to redefine these services as “devices” under the Federal Food, Drug, and Cosmetic Act (FDCA).
For physicians, health systems, and software innovators advancing therapeutic drug monitoring (TDM), this decision protects both patient care and scientific progress. It ensures that tools used to personalize therapy remain within the appropriate regulatory framework of the CLIA, not the FDA, and clears the way for continued innovation in precision dosing.
The FDA’s Attempt to Redefine Laboratory Services
In May 2024, the FDA issued a final rule stating that all in vitro diagnostic products (IVDs), including those developed and used within certified laboratories, should be regulated as devices. This marked a significant shift in approach: for decades, LDTs had been regulated under the Clinical Laboratory Improvement Amendments (CLIA), which govern the quality and validity of lab-based services.
Under the FDA’s redefinition, even internally developed test methods, algorithms, and software used to interpret results could fall under device regulations. That meant labs and physicians using tools to guide personalized dosing, especially in ways not explicitly listed on drug labels, would need FDA clearance before using them.
The Court’s Response: FDA Overstepped
In March 2025, the U.S. District Court for the Eastern District of Texas rejected the FDA’s rule, stating that:
- LDTs are professional medical services, not physical products.
- Congress created CLIA as a separate regulatory framework to govern clinical lab testing.
- The FDA has no statutory authority to regulate lab-developed methodologies as devices.
- Expanding the definition of “device” would have far-reaching implications, potentially subjecting surgeries, physical exams, and any physician-performed procedure using instruments to FDA device oversight.
The ruling vacated the final rule entirely, not just in part, signaling strong judicial pushback against regulatory overreach.
“FDA’s asserted jurisdiction over laboratory-developed test services as ‘devices’ under the FDCA defies bedrock principles of statutory interpretation, common sense, and longstanding industry practice.”
What This Means for Therapeutic Drug Monitoring
TDM plays an essential role in optimizing outcomes for patients on biologics, particularly in complex disabling conditions like inflammatory bowel disease (IBD).
These services are dynamic, patient-specific, and data-driven. They are not physical goods. The court’s ruling preserves the ability for clinicians to use these tools without unnecessary regulatory barriers, and it validates the use of software-based services that support personalized care.
A Clear Path Forward: How Baysient Supports Personalized Dosing
For physicians and health systems currently using Baysient’s iDose or T3, this decision ensures you can confidently continue leveraging precision TDM to improve clinical outcomes and reduce costs.
Baysient’s software service helps providers move beyond one-size-fits-all dosing recommendations. By incorporating real-time lab data and patient-specific characteristics, our system supports:
- Improved patient therapeutic opportunity through targeted therapeutic exposure
- Proactive TDM that prevents loss of response before it begins
- Reduction in ADA development, minimizing immunogenicity risks
- Greater cost efficiency by avoiding ineffective therapy
- Enhanced physician control over therapy adjustments based on real-world data
This ruling confirms that, when used by or under the supervision of a health care professional, Baysient’s tools can continue to deliver value to providers and patients alike, without facing inappropriate device regulation.
Personalized Dosing Is Protected and Needed
Precision dosing is essential to the future of care in biologics. With this legal clarity, providers can move forward with confidence, knowing they can use lab data and algorithmic insights to guide better decisions, reduce risk, and improve therapeutic opportunity equality.
Want to learn how Baysient can help you bring personalized dosing to your practice? Schedule a demo today.
