Owning an instrument calibrated at the national standards lab does not make a measurement traceable. NIST says so itself. The person reporting the result must document the process used and describe the chain of calibrations that links it to a specified reference, with the instrument calibrated at NIST as only one link in that chain.
An unbroken chain
NIST’s policy directive on metrological traceability took effect on May 31, 2019. It adopts the definition in the International Vocabulary of Metrology: a measurement result can be related to a reference through a documented unbroken chain of calibrations, each contributing to the measurement uncertainty. The reference is typically a national or international standard, in particular the realizations of the units of the International System of Units, the SI.
The division of labor is spelled out. NIST assures traceability only for the results it provides itself, directly or through an official program. Other organizations answer for their own results, and for linking them to the national reference standards NIST maintains.
The agency is also blunt about the limits. Traceability alone does not show that a measurement is fit for its purpose. That depends on whether the uncertainty attached to the value is small enough for the job.
NIST provides calibrations, standard reference materials, standard reference data and laboratory accreditation services to help customers build their chains. Its National Voluntary Laboratory Accreditation Program gives third-party accreditation to testing and calibration laboratories. Accreditation, NIST notes, is a formal recognition that a laboratory is competent to carry out specific tasks. It does not approve any particular product.
From the lab to the food supply
The same idea, tracking something back through every hand it passed through, drives a very different rule at the Food and Drug Administration. Its Food Traceability Final Rule, which implements Section 204(d) of the FDA Food Safety Modernization Act, sets recordkeeping requirements for anyone who manufactures, processes, packs or holds foods on the Food Traceability List.
The aim, the FDA says, is faster identification and rapid removal of potentially contaminated food from the market, resulting in fewer foodborne illnesses and deaths.
At the core of the rule, covered firms keep records containing Key Data Elements tied to specific Critical Tracking Events. Those events are harvesting, cooling before initial packing, initial packing of a raw agricultural commodity other than a food from a fishing vessel, first land-based receiving of a food from a fishing vessel, shipping, receiving and transformation of the food. Firms must give information to the FDA within 24 hours, or within a reasonable time the agency has agreed to. The rule covers domestic and foreign firms producing food for U.S. consumers along the whole farm-to-table chain.
The deadline has slipped. The original compliance date was January 20, 2026. The FDA proposed extending it by 30 months, to July 20, 2028, and a 2026 appropriations act directed the agency not to enforce the rule before then. The FDA has also announced a draft enforcement discretion policy for certain smaller retail food establishments and restaurants, and a virtual public meeting on November 6, 2026 on lot-level tracking and possible compliance flexibilities.
Sources
- Metrological Traceability: Frequently Asked Questions and NIST Policy (NIST Technical Note 2156)
- FSMA Final Rule on Requirements for Additional Traceability Records for Certain Foods (FDA)
