Accredited laboratory testing is testing performed by a lab that an independent accreditation body has formally judged competent to run those specific tests against a recognized international standard. That judgment is what gives the results weight with federal regulators, trading partners, and courts. Several U.S. programs, including consumer product safety, food safety, and drinking water compliance, will not accept data from a non-accredited facility, so the choice of lab is often a compliance decision before it is a technical one.
Accreditation Is Not the Same as Certification
The two words get swapped in conversation, but they describe different things. Accreditation is a third-party evaluation confirming a lab is technically competent to perform specific tests: whether its people, equipment, and methods actually produce valid results. Certification usually means an organization’s management system meets a general quality framework such as ISO 9001. A company can hold ISO 9001 certification and still lack the competence to run any particular test reliably.
The practical difference shows up when a manufacturer needs to prove a children’s toy meets a safety rule. What matters is a lab accredited for that exact test, not one waving a general quality certificate. Accreditation bodies themselves are governed by ISO/IEC 17011, which sets requirements for how they evaluate and monitor the labs they accredit.1International Organization for Standardization. ISO/IEC 17011:2017 – Conformity Assessment
The Standards Labs Are Accredited Against
ISO/IEC 17025 for Testing and Calibration
ISO/IEC 17025 is the benchmark for testing and calibration laboratories worldwide. It covers competence, impartiality, and consistent operation, from staff qualifications to the validity of test methods.2International Organization for Standardization. ISO/IEC 17025 – General Requirements for the Competence of Testing and Calibration Laboratories Any organization performing testing, sampling, or calibration that wants externally recognized results can pursue it.3International Organization for Standardization. ISO/IEC 17025 – Testing and Calibration Laboratories
A central requirement is metrological traceability: measurement results must connect back to the International System of Units through an unbroken chain of calibrations. Where traceability is not possible for a given measurement, the lab documents why and identifies an alternative reference. Equipment calibration records, method validation, and documented uncertainty calculations all feed that chain.
Labs accredited to 17025 also participate in proficiency testing, analyzing unknown samples and comparing their results with other accredited facilities. That external check catches systematic errors internal quality controls can miss.4ANSI National Accreditation Board. Proficiency Test Provider
ISO 15189 for Medical Laboratories
Clinical and diagnostic labs work under ISO 15189, which layers concerns unique to patient care on top of measurement accuracy: how samples are collected and handled before analysis, how results are reported to clinicians, and how the lab manages workflow from requisition to result.5International Organization for Standardization. ISO 15189:2022 – Medical Laboratories – Requirements for Quality and Competence The standard also covers point-of-care testing performed at or near the patient. A2LA currently accredits medical labs to the 2022 version, which requires demonstrated continuous improvement.6A2LA. Clinical Testing Lab Accreditation – ISO 15189 and CLIA
When Federal Law Requires an Accredited Lab
Accreditation is not always optional. In several programs, results from a non-accredited lab have no legal weight, no matter how technically sound they look.
Children’s Products
Every manufacturer or importer of a children’s product subject to a safety rule must have that product tested by a third-party laboratory that the Consumer Product Safety Commission has accepted and accredited for the relevant tests. Based on that testing, the manufacturer issues a Children’s Product Certificate confirming compliance.7U.S. Consumer Product Safety Commission. Third-Party Testing Laboratory Accreditation and Small Entity Compliance Guide A report from a non-accredited lab will not satisfy CPSC, and importing or distributing without a valid certificate exposes the company to enforcement.
Food Under FSMA
The FDA’s Laboratory Accreditation for Analyses of Foods (LAAF) program was established under Section 422 of the Federal Food, Drug, and Cosmetic Act.8ANSI National Accreditation Board. FDA Laboratory Accreditation for Analyses of Foods (LAAF) Program Owners and importers must use a LAAF-accredited laboratory when testing food to remove it from an import alert, when supporting admission of detained imported food, when complying with specific regulations for shell eggs, sprouts, or bottled drinking water, or when responding to a directed food laboratory order from the FDA.9U.S. Food and Drug Administration. Laboratory Accreditation for Analyses of Foods (LAAF) Program and Final Rule FDA publishes a registry of recognized accreditation bodies and LAAF-accredited labs.
Drinking Water
Labs analyzing public drinking water samples for regulatory compliance must be certified by the EPA or the relevant state authority. Certification requires successful analysis of proficiency testing samples, use of EPA-approved methods, and passing periodic on-site audits.10U.S. Environmental Protection Agency. Basic Information about Analytical Methods and Laboratory Certification under the Safe Drinking Water Act Water systems that submit compliance data from uncertified labs risk violations.
How a Lab Becomes Accredited
Before any auditor visits, the lab assembles a documentation package. The cornerstone is a quality manual describing the management system, organizational structure, and quality policies. Alongside it sit standard operating procedures for every test the lab wants on its scope of accreditation, written in enough detail that any qualified technician could follow them and reach the same result. Application forms require the lab to define the exact scope of services, facility locations, and key personnel such as the designated quality manager. Evidence of staff training, instrument calibration certificates, and proficiency testing records go with it. Gaps in this paperwork are the most common reason applications stall before an auditor sees the building. FDA publishes its own laboratory manual of quality policies aligned to ISO 17025 as a reference for labs preparing documentation.11U.S. Food and Drug Administration. Laboratory Manual of Quality Policies – ISO 17025 Requirements
Once the accreditation body accepts the package, it schedules an on-site assessment. Auditors observe technicians running actual tests, verify that daily practice matches the written procedures, check calibration records, interview staff, and follow samples through the lab. A well-written manual does not help if the people at the bench are not working from it.
After the visit, auditors issue a report listing any nonconformities. The lab has a set window to respond with a corrective action plan. At A2LA, that window is 30 days from the closing meeting.12A2LA. Corrective Actions – A Breakdown The plan must identify the root cause of each finding and describe steps to prevent recurrence; fixing a symptom without addressing why it happened will not satisfy the auditors. Resolve everything to the accreditation body’s satisfaction and the lab receives a certificate along with a scope document listing the specific tests it is authorized to perform. Failure to address findings can mean denial, or for existing holders, suspension.
The whole process typically runs nine months or more from application to certificate.13AIHA Laboratory Accreditation Programs. Prepare for Accreditation
Keeping Accreditation Active
Earning accreditation is not a one-time event. Accreditation bodies run surveillance audits on an annual basis, and a full reassessment takes place every four years to confirm the lab still meets the standard.14United Kingdom Accreditation Service. ISO/IEC 17025 for Laboratory Testing and Calibration Between audits, the lab runs its own internal quality checks, keeps proficiency testing current, and updates procedures whenever methods or equipment change.
Labs that let internal systems drift face a painful correction when auditors return. Common problems: equipment that has fallen out of calibration, staff who missed refresher training, and procedures updated on paper but never communicated to the technicians actually running the tests.
How to Verify a Lab Before You Send Work
Anyone commissioning testing can confirm a lab’s credentials through the online directories maintained by U.S. accreditation bodies. The three most commonly encountered are ANAB, which accredits testing, calibration, medical, forensic, and dimensional measurement labs among others;15ANSI National Accreditation Board. Laboratory Accreditation Programs A2LA, which covers a wide range of testing and calibration disciplines including clinical testing under ISO 15189;6A2LA. Clinical Testing Lab Accreditation – ISO 15189 and CLIA and NVLAP, operated by NIST, which accredits labs against ISO/IEC 17025 in response to legislative mandates and agency requests.16National Institute of Standards and Technology. National Voluntary Laboratory Accreditation Program (NVLAP)
Two things to check on every directory listing: the expiration date and the scope document. A lab accredited for chemical analysis of metals is not automatically accredited for microbiological testing, even when the same building offers both. Accreditation that has lapsed, or that does not cover the specific test you need, is functionally the same as no accreditation at all.
For work crossing borders, the ILAC Mutual Recognition Arrangement lets signatory accreditation bodies recognize each other’s accreditations, so results from a lab accredited in one participating economy are accepted in others under the principle “accredited once, accepted everywhere.”17International Laboratory Accreditation Cooperation. ILAC MRA and Signatories