FDA 510(k) Glossary · regulatory

Substantial Equivalence

Substantial equivalence is the regulatory standard governing FDA 510(k) clearance. A new medical device is substantially equivalent to a predicate device if it has the same intended use and either identical technological characteristics, or different characteristics that do not raise new questions of safety or effectiveness.
Dataset Insight - 510k Database (166,200 records, 1980–2025)
99.7% of 510(k) submissions in the dataset resulted in a Substantially Equivalent determination. 464 received a Not Substantially Equivalent (DENG) decision.

Definition

Substantial equivalence is the central legal standard of the FDA 510(k) Premarket Notification pathway. Under Section 510(k) of the Federal Food, Drug, and Cosmetic Act, the FDA grants clearance - not approval - when it determines that a new device is substantially equivalent to a legally marketed predicate device.

The Two-Part Test

  1. Same intended use: The new device must have the same intended use as the predicate. If the intended use differs, the device is automatically not substantially equivalent regardless of technological similarity.
  2. Same or different technological characteristics: If technological characteristics differ, the FDA evaluates whether those differences raise new questions of safety or effectiveness. If they do not - and the device performs at least as well as the predicate - substantial equivalence may still be found.

Decision Outcomes

Decision CodeMeaningRecords in Dataset
SESESubstantially Equivalent~163,000+
SESK / SESU / SEKD / SESP / SESDSubstantially Equivalent (variants)~2,700
DENGNot Substantially Equivalent464

Legal Significance

The U.S. Supreme Court addressed the substantial equivalence standard in Medtronic, Inc. v. Lohr, 518 U.S. 470 (1996), noting that the 510(k) process focuses on equivalence rather than independent safety and effectiveness evaluation. The National Academy of Medicine has similarly stated that the process cannot function as a full premarket safety review while the clearance standard remains substantial equivalence.

Dataset Insights

MetricValue
SE determinations (cleared)165,719 (99.7%)
NSE determinations (denied)464 (0.28%)
Panel with most NSE decisionsMicrobiology (62 of 7,038)
Panel with fewest NSE decisionsDental (9 of 12,535)
Average days to SE decision~129 days

Browse all substantially equivalent clearances

FDA References

Related Terms

Predicate Device - Not Substantially Equivalent - De Novo Classification - 510(k) Premarket Notification

Frequently Asked Questions

Substantial equivalence is the legal standard under Section 510(k) of the FD&C Act. A device is substantially equivalent to a predicate if it has the same intended use and its technological characteristics do not raise new safety or effectiveness questions. The FDA issues a clearance - not an approval - when substantial equivalence is established.

The FDA applies a sequential two-part test: (1) Does the new device have the same intended use as the predicate? If not, it is automatically not substantially equivalent. (2) If the intended use is the same, do the technological characteristics raise new safety or effectiveness concerns?

No. The FDA does not approve 510(k)-cleared devices - it determines they are cleared for marketing based on substantial equivalence. Approval is reserved for Class III devices reviewed under the Premarket Approval (PMA) process, which requires clinical evidence of safety and effectiveness.

If the FDA issues a Not Substantially Equivalent (NSE) determination, the manufacturer cannot market the device as submitted. Options include modifying the submission with a new predicate, pursuing the De Novo pathway if the device is low-to-moderate risk, or applying for Premarket Approval (PMA).