health · family: the regulator demands evidence that cannot exist
nearly eighty thousandtests, no fda oversight
Nearly 80,000 laboratory developed tests, including tests used for cancer and genetic diagnoses, operate with no FDA oversight of their accuracy
Problem statement
Laboratory developed tests (LDTs) — in vitro diagnostic tests designed, manufactured, and used within a single laboratory — have mostly gone without FDA premarket review under longstanding enforcement discretion. Unlike commercial in vitro diagnostics (IVDs), most LDTs have not had FDA review of their analytical and clinical validation and are not held to device requirements such as adverse event reporting. This creates a regulatory gap in which tests whose quality can vary widely are used for critical clinical decisions including cancer diagnosis, prenatal screening, and infectious disease detection. The FDA's 2024 attempt to close this gap through rulemaking was struck down in court and subsequently rescinded. The district court's opinion, as reported by Sidley Austin, put the rule's reach at nearly 80,000 existing tests offered by almost 1,200 laboratories, and the Congressional Research Service says the ruling has the practical effect of removing most if not all LDTs from FDA's regulatory purview.
Why this matters
The FDA's rule would have affected nearly 80,000 existing tests offered by almost 1,200 laboratories, according to the district court's opinion as reported by Sidley Austin. LDTs include tests for cancer biomarkers, rare diseases, and prenatal screening. Because these tests guide critical health care decisions, wrong results can harm patients. Direct-to-consumer genetic tests that report disease risk are one subset of higher-risk LDTs over which the FDA had traditionally asserted authority. Quality problems have been recorded: the Congressional Research Service notes the FDA's report that its COVID-19 test policy, combined with the lower evidence standard for emergency use, resulted in the use of LDTs that "proved to have performance problems or to be poorly validated." In genomics and next-generation sequencing, The Pathologist's analysis warns, patients may receive very different results depending on where their sample is tested.
What’s been tried and why it hasn’t worked
The FDA issued a final rule in May 2024 establishing a phaseout of enforcement discretion for LDTs, classifying them as IVDs subject to premarket review. A federal district court vacated the rule in March 2025, finding the FDA exceeded its statutory authority, and the FDA formally rescinded it in September 2025, restoring the regulatory gap. Legislative proposals — including the VALID Act — have attempted to create a new regulatory framework for LDTs, but none have been enacted. Some representatives of clinical laboratories have long argued that LDTs are clinical services rather than medical products and so fall outside FDA's purview, and an analysis in The Pathologist judges that implementing the rule would have been burdensome for some laboratories, especially smaller ones. LDTs are subject to CLIA (Clinical Laboratory Improvement Amendments) oversight: the laboratories that offer them are CLIA-certified and inspected. But the FDA's FAQ page, written before the ruling, notes that CLIA inspections do not check whether the tests themselves comply with the device-law requirements designed to ensure safety and effectiveness for their intended purpose. Proficiency testing programs for LDTs are inconsistent and limited in scope. In genomics and next-generation sequencing, validation methods vary, reporting standards differ, and interpretation frameworks diverge across laboratories.
What would unlock progress
Congressional legislation creating a tailored regulatory framework for LDTs — distinct from the traditional IVD pathway but requiring analytical validation and adverse event reporting — would directly address the statutory authority gap that doomed the FDA's rulemaking approach. Alternatively, a voluntary accreditation program with transparent performance benchmarking (analogous to how CAP accreditation works for laboratories) that publicly reports LDT-level analytical validity data could create market-driven quality pressure. Standardized reference materials and proficiency testing panels for high-complexity LDTs (especially NGS-based tests) would enable meaningful quality comparisons even without new regulation.
Entry points for student teams
A student team could design a standardized benchmarking framework for a specific category of LDTs (e.g., oncology NGS panels) using publicly available reference samples and variant databases (e.g., Genome in a Bottle, ClinVar) to quantify inter-laboratory variability. Another entry point would be developing a transparency platform that aggregates and displays publicly available LDT performance data, helping clinicians and patients understand the evidence behind the tests they rely on. Teams with backgrounds in genomics, laboratory science, data science, or health policy would be well-suited. A scoped semester project could focus on a single test category, the public Genome in a Bottle benchmarks, and whatever proficiency testing results a program or partner laboratory will share.
Genes
Structural cousins: stuck the same way, in other fields
Sources
FDA, "Definitions and General Oversight: Laboratory Developed Tests FAQs," FDA CDRH, accessed 2026-02-19 go to source ↗
Working notes
Notes made while writing and checking this brief, shown as written. They use working shorthand.
Key references include the FDA LDT FAQs page, Sidley Austin analysis of the court ruling vacating the FDA's LDT rule (April 2025, https://www.sidley.com/en/insights/newsupdates/2025/04/fdas-laboratory-developed-tests-ldt-rule-struck-down-in-major-test-of-loper-bright), The Pathologist analysis (May 2025), and Congressional Research Service report on FDA regulation of LDTs. The regulatory gap has persisted since 1976 — the FDA has exercised enforcement discretion over LDTs for nearly fifty years while the technology has transformed from simple, low-volume tests to complex multi-analyte assays and AI-driven molecular diagnostics. Tagged as "worsening" because LDT complexity and clinical reliance are growing while the regulatory framework remains frozen. This brief connects to broader themes of regulatory lag in fast-moving diagnostic technology; see also health-aiml-device-regulatory-lifecycle for analogous challenges in AI-based diagnostics.
Reconciliation 2026-09-30: Whole write-up read against every source it names, all fetched 2026-09-30. Read in full: the FDA page on the Source line (https://www.fda.gov/medical-devices/laboratory-developed-tests-faqs/definitions-and-general-oversight-laboratory-developed-tests-faqs, direct; the page says its content is current as of 01/15/2025, which is before the court ruling) together with six of its seven sibling FAQ pages and the FDA's parent Laboratory Developed Tests page (https://www.fda.gov/medical-devices/in-vitro-diagnostics/laboratory-developed-tests); the Sidley Austin update dated April 3, 2025 (direct, at the address given above); The Pathologist's May 2025 piece, "Laboratory Developed Tests: Did We Really Win?" by Caitlin Raymond, dated 05/16/2025 (the publisher's site timed out, so it was read from the Internet Archive copy at https://web.archive.org/web/20260609083625/https://thepathologist.com/issues/2025/articles/may/laboratory-developed-tests-did-we-really-win); and the Congressional Research Service In Focus IF11389, "FDA Regulation of Laboratory-Developed Tests (LDTs)," updated December 19, 2025 (congress.gov refused the request, so it was read from the copy at https://www.everycrsreport.com/reports/IF11389.html). The write-up does not give an address for the last two; these are the pieces that match its description. Changes: (1) The titles and two body sentences said "12,000+" tests. No source gives that figure. Sidley Austin, reporting the district court's opinion, says the rule "would have affected nearly 80,000 existing tests offered by almost 1,200 laboratories." The text now gives those two figures, attributed to Sidley Austin's report of the court's opinion, and attributes to CRS the statement that the ruling removes "most if not all" LDTs from FDA's purview. The long title changed from "12,000+ Laboratory Developed Tests Used for Cancer and Genetic Diagnoses Operate with No Federal Accuracy Oversight" to "Nearly 80,000 Laboratory Developed Tests, Including Tests Used for Cancer and Genetic Diagnoses, Operate with No FDA Oversight of Their Accuracy", and the display title from "Twelve Thousand Tests, Zero Oversight" to "Nearly Eighty Thousand Tests, No FDA Oversight". "Zero" and "no federal" became "no FDA" because the sources describe the tests as still marketed under CLIA, which is a federal program; what the sources support is that the ruling removes "most if not all" of these tests from the FDA's purview (CRS). (2) The text said none of the legislative proposals were enacted "due to opposition from laboratory industry stakeholders, academic medical centers, and concerns about regulatory burden on small laboratories." No source gives a reason the bills failed. The sentence now says only that none were enacted, and then reports two things the sources do say: that some laboratory representatives have long argued these tests are services outside the FDA's purview (CRS), and that an analysis in The Pathologist, an opinion column, judges that implementing the rule would have been burdensome for some laboratories, especially smaller ones. "Most notably the VALID Act" became "including the VALID Act", which is how Sidley puts it. (3) The text said CLIA "addresses laboratory quality systems and personnel qualifications but was never designed to evaluate the analytical or clinical validity of specific tests." No source says this. The FDA page says these laboratories are CLIA-certified and that CLIA inspections "do not verify that the tests themselves comply with the requirements of the FD&C Act that are designed to ensure that tests have appropriate assurance of safety and effectiveness for their intended purpose"; the sentence now follows that, saying the FDA's FAQ page, written before the ruling (its content is dated 01/15/2025), notes that CLIA inspections do not check whether the tests themselves comply with those requirements. (4) Theranos is not mentioned in any source, and neither are "numerous" cases of sequencing panels giving different results. The sentence now reports the CRS account of poorly validated COVID-19 tests and The Pathologist's warning that patients "may receive very different results, depending entirely on where their sample is tested." (5) "The direct-to-consumer genetic testing market ... reaches millions of consumers" is not in any source; the sentence now gives the CRS statement that such tests are a higher-risk subset over which the FDA had traditionally asserted authority. (6) The list of harms (misdiagnosis, inappropriate treatment, unnecessary surgery, missed diagnoses) is not in any source and was shortened to what the sources support: these tests guide critical health care decisions and wrong results can harm patients. (7) Pharmacogenomics is not named in any source and was removed from both lists of test types. (8) The opening said these tests "are exempt" from premarket review and "do not undergo" FDA validation; CRS says "most of these tests" have not undergone premarket review, and the text now says "mostly" and "most". (9) The last entry point pointed students to "a handful of public proficiency testing datasets"; no public proficiency testing dataset could be found in the sources, so it now points to the public Genome in a Bottle benchmarks and to whatever results a program or laboratory will share. (10) The Source line title now matches the page's own title, "Definitions and General Oversight: Laboratory Developed Tests FAQs". Confirmed in the sources and left as written: the definition of a laboratory developed test (FDA page); the May 2024 final rule, the March 2025 ruling that the FDA exceeded its authority, and the September 2025 rescission (FDA parent page, Sidley, CRS); that the VALID Act did not pass (Sidley); that proficiency testing programs are inconsistent and limited in scope, and that validation, reporting and interpretation differ across laboratories in genomics and sequencing (The Pathologist, an opinion piece); roughly fifty years of enforcement discretion and the shift from simple tests to complex and AI-based ones (The Pathologist, CRS, and the FDA page's references to the 1976 device amendments); Genome in a Bottle (https://www.nist.gov/programs-projects/genome-bottle) and ClinVar (https://www.ncbi.nlm.nih.gov/clinvar/intro/) both describe themselves as public. Could not be checked: the FDA's FAQ page on medical device reporting, which returned an error; and the comparison to CAP accreditation in the proposals section, which no source mentions and which was left as the write-up's own suggestion. The note above says the write-up is tagged "worsening"; the tag block reads "static". A second reader went over every repair the same day, 2026-09-30, against fresh copies of the same sources (The Pathologist piece read from the publisher's own site this time, matching the archive copy), found each repair justified, and reworded three sentences so they say no more than the sources: the Problem Statement no longer says the 80,000 tests "remain on the market", which no source states, and now names Sidley Austin and CRS for the figures and the "most if not all" statement; the burden-on-smaller-laboratories point is now attributed to The Pathologist's analysis; and the CLIA sentence now reports the FDA FAQ page as written before the ruling and paraphrases its inspection statement. All other repairs stand as described above. Genome tags untouched.