FDA medical device regulation is a risk-tiered system: every device sold in the United States is assigned to one of three classes based on the risk it poses, and that class determines which premarket pathway — 510(k) clearance, Premarket Approval (PMA), or De Novo classification — the device must go through before it can be legally marketed. The framework sits in the Federal Food, Drug, and Cosmetic Act (FD&C Act) and its implementing regulations, chiefly 21 CFR Parts 800-898, and is administered by FDA’s Center for Devices and Radiological Health (CDRH). For research institutions, this framework is the backdrop against which a related but distinct question gets asked: whether a specific device used in a specific clinical study is investigational and therefore subject to Investigational Device Exemption (IDE) requirements under 21 CFR Part 812 — a study-level question layered on top of the market-level classification system this guide covers.
Device classification: Class I, II, and III
FDA classifies every medical device into one of three classes under 21 CFR Part 860, based on the level of control necessary to provide reasonable assurance of safety and effectiveness. Classification is device-type-specific — FDA maintains a searchable product classification database mapping thousands of device types to their class — not something a sponsor negotiates case by case, except through the De Novo or reclassification processes described below.
- Class I — low risk, general controls. Subject to the baseline requirements that apply to all devices: registration and listing, labeling, good manufacturing practice under the Quality System Regulation, and adverse event reporting. Roughly 47% of device types are Class I, and most are exempt from premarket notification entirely. Examples: elastic bandages, manual toothbrushes, examination gloves.
- Class II — moderate risk, general controls plus special controls. “Special controls” are device-type-specific requirements layered on top of general controls — performance standards, post-market surveillance, patient registries, special labeling, or FDA guidance documents. Most Class II devices require 510(k) clearance before marketing. Examples: infusion pumps, surgical drapes, most diagnostic imaging systems.
- Class III — highest risk, premarket approval. Devices that sustain or support life, are implanted, or present a potential unreasonable risk of illness or injury. General and special controls alone are considered insufficient; these devices require a Premarket Approval (PMA) application demonstrating reasonable assurance of safety and effectiveness. Examples: implantable pacemakers, heart valves, and most devices with no existing predicate.
510(k) premarket notification and substantial equivalence
Premarket Notification — universally called by its FD&C Act section number, “510(k)” — is the pathway most Class II (and some Class I) devices use. It is not an approval; FDA “clears” a 510(k), it does not “approve” one, and the distinction is not just semantic. A 510(k) does not require the sponsor to independently prove the device is safe and effective. Instead, under the procedures in 21 CFR Part 807, Subpart E, the sponsor must demonstrate the new device is substantially equivalent to a legally marketed “predicate” device — one already on the market with the same intended use and, if it has different technological characteristics, no new questions of safety or effectiveness. Because substantial equivalence review typically relies on existing performance data and bench/comparative testing rather than a fresh clinical trial, 510(k) review is generally faster and less costly than PMA review. FDA recognizes three 510(k) submission types — Traditional, Special (for a device modification by the same manufacturer), and Abbreviated (relying on a recognized consensus standard or FDA guidance) — each with different documentation expectations.
Premarket Approval (PMA)
PMA, governed by 21 CFR Part 814, is FDA’s most stringent device review pathway and applies to Class III devices, along with any device FDA has not down-classified out of the automatic Class III designation that applies to a genuinely novel device type. Unlike a 510(k), a PMA requires the sponsor to submit valid scientific evidence — ordinarily including data from well-controlled clinical investigations conducted under an approved IDE — sufficient for FDA to make an affirmative finding of reasonable assurance of safety and effectiveness, not merely equivalence to something already on the market. A PMA application also includes full manufacturing information, and FDA typically conducts a pre-approval facility inspection before granting approval. PMA review timelines and evidentiary requirements are substantially longer and heavier than 510(k) review, which is why the classification decision early in a device’s development — is this a 510(k) or a PMA product — shapes years of downstream regulatory and clinical-trial planning. For devices where a use error could cause serious harm, FDA also typically expects human factors and usability engineering data as part of that evidentiary package.
De Novo classification: a pathway for novel low- to moderate-risk devices
Not every new device type has a predicate to be “substantially equivalent” to, and not every device without a predicate is high risk enough to warrant PMA’s evidentiary burden. The De Novo classification pathway, codified at 21 CFR Part 860, Subpart D, exists for exactly that gap: a sponsor with a novel device that presents low to moderate risk can petition FDA to create a new Class I or Class II regulatory category (with special controls, if Class II) rather than default into Class III for lack of a predicate. A successful De Novo grant creates a new predicate — meaning later devices of that same type can then use the faster 510(k) pathway by citing the De Novo device itself. De Novo was established by the Food and Drug Administration Safety and Innovation Act (FDASIA) of 2012 and streamlined further by the 21st Century Cures Act of 2016.
510(k) vs. PMA vs. De Novo, at a glance
| Pathway | Typical device class | Core requirement | Governing regulation |
|---|---|---|---|
| 510(k) | Class II (some Class I) | Substantial equivalence to a predicate device | 21 CFR Part 807, Subpart E |
| PMA | Class III | Reasonable assurance of safety and effectiveness, usually via clinical data | 21 CFR Part 814 |
| De Novo | Novel, low-to-moderate risk, no predicate | Risk-based justification for a new Class I/II category | 21 CFR Part 860, Subpart D |
Where clinical study oversight fits in
Device classification and premarket pathways govern whether and how a device reaches the commercial market. A separate but related question governs research institutions directly: when a device — investigational or already cleared/approved — is used in a clinical study, is that use “investigational” under 21 CFR 812.3(g), and if so, is it a significant risk (SR) or nonsignificant risk (NSR) device under 812.3(m)? SR devices require a full Investigational Device Exemption (IDE) application and FDA approval before enrollment begins, in addition to IRB approval; NSR devices qualify for abbreviated IDE requirements under IRB oversight alone. Research administrators and IRBs typically resolve this SR/NSR question, and confirm where the device sits in the classification framework above, before finalizing study budgets, timelines, and monitoring plans.
Special and expedited pathways worth knowing
- Humanitarian Device Exemption (HDE). A distinct, lower-evidentiary-burden pathway under FD&C Act Section 520(m) and 21 CFR Part 814, Subpart H, for devices treating conditions affecting no more than 8,000 U.S. patients per year — see CASRAI’s Humanitarian Use Device (HUD) entry for the full designation and application process.
- Breakthrough Devices Program. An FDA program (established under the 21st Century Cures Act) offering more frequent FDA interaction and prioritized review for devices that provide more effective treatment or diagnosis of life-threatening or irreversibly debilitating conditions. It accelerates review timing and communication; it does not change which pathway (510(k), PMA, or De Novo) the device ultimately goes through, or lower the evidentiary bar that pathway requires.
- Q-Submission (Q-Sub) program. A formal mechanism for sponsors to request FDA feedback — on classification, predicate selection, study design, or data requirements — before a formal submission, reducing the risk of a costly late-stage rejection.
Frequently asked questions
What’s the difference between FDA “clearance” and FDA “approval” for a device?
“Clearance” applies to 510(k) devices, where FDA determines substantial equivalence to an existing predicate. “Approval” applies to PMA devices, where FDA makes an affirmative finding of reasonable assurance of safety and effectiveness based on the sponsor’s own evidence. The two words are not interchangeable in FDA’s own usage, and using the wrong one in labeling or promotional claims is itself a compliance issue.
Does every device need FDA clearance or approval before use in a clinical study?
No. Whether a device needs an approved IDE before a study can begin depends on the SR/NSR determination under 21 CFR 812.3(m), not on its ultimate market classification — see CASRAI’s Investigational Device entry for the full criteria and the exemptions in 812.2(c).
Can a device move from one pathway to another during development?
Yes. A device initially expected to require PMA because it lacks a predicate can instead pursue De Novo if it is genuinely low-to-moderate risk; a device can also be reclassified over time as FDA gathers more information about a device type. Sponsors typically use the Q-Submission program to confirm the correct pathway before committing to a full submission.
Who at a research institution typically manages device regulatory pathway questions?
This usually sits with the institution’s regulatory affairs office or research administration unit working alongside the IRB and the study’s sponsor or investigator — determining classification and pathway is primarily a sponsor/manufacturer responsibility, but institutions engaging in device research need to understand where a given device sits in this framework to scope IRB review, budgeting, and monitoring correctly.
This guide covers the market-level regulatory framework for medical devices. For the study-level question of when a device used in research is “investigational” and what IDE requirements apply, see CASRAI’s Investigational Device entry; for the humanitarian-use pathway specifically, see Humanitarian Use Device (HUD).
