The 510(k) pathway has a built-in gap. It works only when a predicate exists, a legally marketed device the new product can be compared against. But what about a genuinely novel device, one with no predecessor, that is nonetheless low or moderate in risk? Forcing it through premarket approval would be disproportionate; it does not have the risk profile of a Class III device. The De Novo classification request exists to fill exactly that gap.

The pathway is codified in 21 CFR Part 860, Subpart D. Its purpose section, 21 CFR 860.200, lays out both the goal and the two ways a sponsor can reach it. The regulation frames De Novo as a route to classify novel devices that genuinely belong in Class I or II but cannot use substantial equivalence because nothing comparable is on the market.

"The purpose of this part is to establish an efficient, transparent, and thorough process to facilitate De Novo classification into class I or class II for devices for which there is no legally marketed device on which to base a review of substantial equivalence and which meet the definition of class I or class II as described in section 513(a)(1) of the Federal Food, Drug, and Cosmetic Act and § 860.3."— 21 CFR 860.200, source

The two ways into De Novo

The same regulation specifies that a De Novo request can be submitted for a single device type in two situations. The first is reactive: after a device receives a 'not substantially equivalent' (NSE) determination in response to a 510(k) premarket notification, the sponsor can pivot to De Novo rather than abandon the device or escalate to a PMA. An NSE is not a verdict that the device is unsafe; it often just means no adequate predicate exists, which is precisely the condition De Novo was built for.

The second route is direct: if a sponsor determines at the outset that there is no legally marketed device on which to base a substantial-equivalence determination, it can file a De Novo request directly, without first filing a 510(k) that it expects to fail. The direct route became the more common practice as the program matured, sparing sponsors a pro forma 510(k) detour. Either way, the device must meet the Class I or II definition in 21 CFR 860.3, which is the same control-based test that governs all device classification.

Why a De Novo grant matters beyond the one device

The consequential feature of De Novo is what a grant produces. When the FDA grants a De Novo request, it does more than authorize one device, it creates a new device type with its own classification regulation and product code. That new classification typically establishes a predicate for the future. The next company with a similar device no longer faces the no-predicate problem; it can file a 510(k) citing the De Novo-classified device. In effect, a single De Novo can open a 510(k) lane for an entire emerging device category.

The FDA's classification database shows the downstream result. Newer product codes, often in fast-moving areas like software-based devices, frequently originate from De Novo decisions. The entry for 'Radiological Computer-Assisted Triage And Notification Software,' product code QAS under regulation 892.2080 and classified as Class 2, is exactly the kind of novel device-type classification that a De Novo can establish, after which subsequent triage-software submissions can use the 510(k) pathway against it. The pathway is therefore both an entry point for one novel device and a generator of regulatory infrastructure for the devices that follow.

Reading De Novo correctly means holding two facts together. First, it is reserved for novel devices that are low to moderate in risk, Class I or II under the same 860.3 control test, not a shortcut around the rigor a high-risk Class III device would face through PMA. Second, it is the bridge that turns a brand-new device type into a classifiable, and eventually predicate-able, category. The regulation at 21 CFR 860.200 captures both: an 'efficient, transparent, and thorough' process for classifying the devices the 510(k) system, by design, cannot reach on its own.

What the FDA decides when it grants a De Novo

A granted De Novo does three things at once, and Part 860 sets out each of them. It classifies the device into Class I or Class II. It identifies the special controls, where the device is Class II, that the FDA has determined are necessary to provide reasonable assurance of safety and effectiveness, the performance standards, labeling requirements, or postmarket measures that the device type must meet. And it establishes a new classification regulation and product code for the device type. Because special controls travel with the classification, every later device that uses the new type as a predicate inherits the obligation to meet those same controls. The De Novo, in effect, writes the rulebook for a category as it opens it.

This is why De Novo has become central to how the FDA regulates emerging technology, particularly software-driven and computational devices that simply did not exist when their nearest analog reached the market. The classification database is increasingly populated with such product codes, novel diagnostic and decision-support tools first classified through De Novo and now serving as predicates for fast-following submissions. The pathway converts genuine novelty, the absence of any predicate, into durable regulatory structure: a class, a set of controls, a product code, and a predicate the rest of the field can build on. That conversion, more than the single-device authorization, is what makes De Novo distinct from both the 510(k) and the PMA.

For a reader parsing a device's history, a De Novo origin is a useful signal. It indicates the device, or its device type, was novel enough that no predicate existed, yet low-risk enough to avoid premarket approval, and that the FDA built a fresh classification, with its own special controls, to accommodate it. The defining sentence in 21 CFR 860.200 ties it all together: a process to classify into Class I or II the very devices for which substantial equivalence cannot be shown because nothing comparable is on the market.