Is it a medical device, which class, and who is responsible?

Introduction#

Before a company can plan European market entry, it has to settle three questions about its product. The first is whether the product is a medical device or an in vitro diagnostic medical device (IVD), meaning a test that examines samples taken from the human body. The second is which risk class it falls into. The third is which company carries the legal obligations for it.

The answers decide whether a notified body must assess the product before it can carry the CE marking. A notified body is an assessment organisation designated under the regulations, and the CE marking is the mark the manufacturer affixes once the device is shown to meet them. Whether a notified body takes part drives much of the cost and timing of market entry.

The answers come from the Medical Device Regulation, Regulation (EU) 2017/745 (MDR), and the In Vitro Diagnostic Medical Device Regulation, Regulation (EU) 2017/746 (IVDR). Guidance from the Medical Device Coordination Group (MDCG), made up of representatives of the Member States' regulators, shows how the Member States read them, although its views do not bind anyone in law. The law is stated as consolidated on 19 July 2026 for the MDR and on 10 January 2025 for the IVDR, and was checked on 29 September 2026.

Four illustrative products recur in later chapters, and section 8 works out their answers. They are a wearable cardiac monitor from a US company and triage software enabled by artificial intelligence (AI) from a European company. The other two are a spinal implant certified under the former directive and a near-patient cardiac troponin test from a Swiss company.

1. Is the product a medical device or an IVD?#

Whether a product is a medical device depends on what its manufacturer intends it for. Any instrument, apparatus, appliance, software, implant, reagent, material or other article is a medical device if the manufacturer intends it for one of the listed medical purposes in human beings. The purposes include diagnosis, prevention, monitoring, prediction, prognosis, treatment and alleviation of disease. A product that achieves its principal intended action by pharmacological, immunological or metabolic means falls outside the definition. (MDR Art. 2(1))

An IVD is a medical device of a particular kind. Its manufacturer intends it to be used in vitro to examine specimens from the human body. The aim, solely or principally, is to give information on one or more of six listed matters. Examples are a pathological state, a predisposition to a disease, or the likely response to treatment. (IVDR Art. 2(1), 2(2))

Products for general laboratory use and research-use-only products are outside the IVDR. The exception is a product whose manufacturer, in view of its characteristics, specifically intends it for in vitro diagnostic examination. (IVDR Art. 1(3))

(MDR Art. 1(2), 1(7), 2(1), 2(2); Annex VIII s. 3.2; IVDR Art. 1(4); MDR recital 19; MDCG 2024-11, pp. 4, 7, 10 and 11; MDCG 2021-24 rev.1, pp. 13 and 46)

The MDR also excludes medicinal products, cosmetics, food and several classes of biological material. A device with both a medical and a non-medical purpose must meet both sets of requirements. (MDR Art. 1(3), 1(6))

Software qualifies when the manufacturer intends it for a listed medical purpose. Recital 19 of the MDR adds that it must be so intended in its own right, and MDCG 2019-11 rev.1 requires a medical purpose of its own. Software for general purposes does not qualify, even when used in a healthcare setting. (MDR Art. 2(1); MDR recital 19; MDCG 2019-11 rev.1, p. 8)

MDCG 2019-11 rev.1 adds a further step the definition does not state in these words: the software must act for the benefit of individual patients. Simple arithmetic can still qualify. The Manual on borderline and classification records agreement that a point-of-care score calculator is a medical device. (MDCG 2019-11 rev.1, pp. 12 and 13; Manual v5, pp. 17, 18 and 26)

Where software draws on IVD data and other device data together, MDCG 2019-11 rev.1 applies the IVDR if the IVD data substantially drive the intended purpose. Neither regulation states that test; it is the guidance's own. (MDCG 2019-11 rev.1, pp. 14 and 15)

What MDCG guidance is worth#

The MDCG is made up of members appointed by each Member State to represent its competent authorities. It is chaired by a representative of the Commission. (MDR Art. 103(2), (5))

Each MDCG document listed in the Sources states that its views are not legally binding. Each also states that only the Court of Justice of the European Union can give a binding interpretation of Union law. The guidance therefore shows how the Member States' representatives read the regulations. (MDCG 2019-11 rev.1, cover page)

A classification dispute with a notified body is decided by a national competent authority, as section 5 explains. (MDR Art. 51(2); Manual v5, pp. 5 and 6)

The label "our reading" marks the authors' own interpretation. Our reading is that a manufacturer may depart from the way a guidance document reads the regulations, provided it sets out in writing why it disagrees.

2. What the intended purpose covers#

Intended purpose is the use for which a device is intended according to the data the manufacturer supplies. Those data are on the label, in the instructions for use, in promotional or sales materials or statements, and in the clinical evaluation. The classification rules are applied according to it. (MDR Art. 2(12); Annex VIII s. 3.1)

The IVDR lists the same sources and adds what the manufacturer specifies in the performance evaluation. Performance evaluation is the assessment and analysis of data to establish or verify a device's scientific validity, its analytical performance and, where applicable, its clinical performance. (IVDR Art. 2(12), 2(44))

Because sales statements count, a sales presentation that claims more than the label can widen the intended purpose and so raise the class. MDCG 2019-11 rev.1 says software's intended purpose should describe all its medical functions without ambiguity, since ambiguity can lead to misclassification. (MDR Art. 2(12); MDCG 2019-11 rev.1, p. 7)

3. Which class does the product take?#

The MDR divides devices into classes I, IIa, IIb and III, and the IVDR divides IVDs into classes A, B, C and D. Both base the class on the intended purpose and the inherent risks, under the rules in their Annex VIII. (MDR Art. 51(1); IVDR Art. 47(1))

How the MDR rules are organised#

(MDR Annex VIII)

Four sections of Chapter II govern combinations, software, unspecified parts of the body and overlapping rules:

(MDR Annex VIII s. 3.2 to 3.5)

Section 3.2 applies the rules separately to each device in a combination. MDCG 2021-24 rev.1 gives an example in which a manufacturer applies the highest class to the whole combination. In the guidance, giving the whole combination a single class needs its own justification. (MDR Annex VIII s. 3.2; MDCG 2021-24 rev.1, p. 17)

Rule 11: software#

Rule 11 classifies software by the decisions its information is used for and by the impact those decisions may have.

(MDR Annex VIII, Rule 11)

MDCG 2019-11 rev.1 reads the first paragraph of Rule 11 as generally applicable to software with a medical purpose. To judge the impact of a decision, it asks whether a decision taken on incorrect information from the software is reasonably likely to cause the harm the rule describes. (MDCG 2019-11 rev.1, pp. 17 and 18)

MDCG 2021-24 rev.1 adds the intended population and the context of use, such as intensive care or home use. These factors are the guidance's own, so a manufacturer's classification rationale should first address the wording of Rule 11 itself. (MDCG 2021-24 rev.1, p. 47; MDR Annex VIII, Rule 11)

Under Section 3.3, software that drives a device takes that device's class, so software driving a class I device would itself be class I. Our reading is that, where the same software also meets Rule 11 in its own right, Section 3.5 applies the stricter of the two classes. MDCG 2019-11 rev.1 reaches a similar result by treating the class of the driven device as the lowest class the software can take. (MDR Annex VIII s. 3.3, 3.5, Rule 11; MDCG 2019-11 rev.1, p. 16)

IVD classes#

The IVDR has seven rules of its own, and MDR Rule 11 does not apply to IVDs. None of the seven is a software rule. Rule 6 is the default: an IVD that no other rule covers is class B, and class B needs a notified body. (IVDR Art. 47(1); Annex VIII, Rules 1 to 7; Art. 48(9))

The IVDR's implementing rules on combinations, accessories and software that drives a device match the MDR's. Both regulations apply the higher class where several rules apply, so each claim added to the label can bring in a stricter rule and raise the class. (IVDR Annex VIII s. 1.2 to 1.4, 1.9; MDR Annex VIII s. 3.5)

Where the MDR and the IVDR differ#

(MDR Annex VIII, Rules 1, 11, 13; Art. 10(3), 52(6), 52(7); IVDR Annex VIII, Rule 6; Art. 10(3), 48(3), (7), (9), (10))

4. Does a notified body take part?#

Conformity assessment is the process that demonstrates whether a device meets the regulation's requirements. Once conformity is shown, the manufacturer draws up the EU declaration of conformity and affixes the CE marking. (MDR Art. 2(40), 10(6); IVDR Art. 2(32), 10(5))

The routes are built from four annexes:

(MDR Annexes IX, X and XI; Art. 52; IVDR Annex IX)

Article 52 of the MDR and Article 48 of the IVDR attach a route to each class:

(MDR Art. 52(3) to (7), 54; IVDR Art. 48(3) to (10); MDCG 2019-15 rev.1, p. 16)

The sample of technical documentation that the notified body assesses depends on two ways of grouping devices. A generic device group is a set of devices with the same or similar intended purposes, or a shared technology, classified in a generic way. A category of devices is the grouping by which the documentation is sampled for MDR class IIa and IVDR class B. Neither regulation defines the term, so how a notified body draws its categories is a question to put to each body. (MDR Art. 2(7), 52(6); IVDR Art. 2(8), 48(9))

A companion diagnostic is a test essential for the safe and effective use of a particular medicinal product. One example is a test that identifies the patients most likely to benefit from it. (IVDR Art. 2(7))

The class I exceptions. A class I device placed on the market sterile, with a measuring function, or as a reusable surgical instrument goes to a notified body. MDCG 2021-24 rev.1 labels these variants Is, Im and Ir. (MDR Art. 52(7); MDCG 2021-24 rev.1, p. 7)

The same guidance gives three criteria that together indicate a measuring function: a quantitative measurement, a result in acceptable units, and an implied accuracy that matters to patient safety. Under the IVDR, the only class A device that needs a notified body is a sterile one. (MDCG 2021-24 rev.1, p. 14; IVDR Art. 48(10))

A wearable that one team treats as class I and another as class IIa leads to two different projects, with different budgets and launch dates. The class IIa product needs a notified body, and the class I product may need one too if it has a measuring function. (MDR Art. 52(6), (7); MDCG 2021-24 rev.1, p. 14)

Chapter 8, Which notified body can assess the device, and how does the work with it run?, covers the work on each route and the choice between routes.

5. What happens when the manufacturer and the notified body disagree on the class?#

A disagreement between a manufacturer and its notified body on how Annex VIII applies goes to a competent authority for decision. That is the authority of the Member State where the manufacturer has its registered place of business. (MDR Art. 51(2); IVDR Art. 47(2))

A manufacturer with no registered place of business in the Union may not yet have designated an authorised representative. In that case the dispute goes to the authority where the authorised representative referred to in Annex IX, Section 2.2, has its registered place of business. (MDR Art. 51(2); IVDR Art. 47(2))

If the notified body sits in another Member State, the deciding authority first consults the authority that designated it. The deciding authority notifies the MDCG and the Commission of its decision. (MDR Art. 51(2); IVDR Art. 47(2))

At the request of a Member State, or on its own initiative, the Commission can also decide by implementing act how Annex VIII applies to a device, category or group. It does so after consulting the MDCG. On the same footing it can reclassify for reasons of public health, based on new scientific evidence or on information from vigilance and market surveillance. (MDR Art. 51(3), (4))

The Manual on borderline and classification states that individual products are classified case by case by the Member State authorities, under the supervision of the courts. (Manual v5, pp. 5 and 6)

6. Who is responsible for the product?#

The economic operators are the manufacturer, the authorised representative, the importer and the distributor. The MDR adds the person who combines or sterilises systems and procedure packs. (MDR Art. 2(35), 22; IVDR Art. 2(28))

(MDR Art. 2(30), 2(32) to (34), 10, 11, 13, 14; IVDR Art. 2(23) to (27))

Manufacturer. A manufacturer that outsources design or production keeps all its obligations. The manufacturer needs financial coverage for its potential liability under the Product Liability Directive, 85/374/EEC. The coverage is proportionate to the risk class, the type of device and the size of the company. (MDR Art. 2(30), 10(16); MDR recital 31)

Before placing a device other than a custom-made device on the market, the manufacturer assigns it a UDI. It also provides the device's core data to the UDI database. (MDR Art. 27(3), 29(1))

Person responsible for regulatory compliance. Each manufacturer needs one, with defined qualifications or experience. A micro or small enterprise may have that person permanently and continuously at its disposal instead of on its staff. The authorised representative needs its own, and MDCG 2022-16 reads this as a different person from the manufacturer's. (MDR Art. 15(1), (2), (6); MDCG 2022-16, p. 9)

Authorised representative. A manufacturer not established in a Member State may place a device on the Union market only if it designates a sole authorised representative. The designation is valid once the representative accepts it in writing, and covers at least all devices of the same generic device group. (MDR Art. 11(1), (2); IVDR Art. 11)

MDCG 2022-16 reads this as allowing different representatives for different generic device groups, with no group covered twice. The core manufacturer obligations cannot be delegated to the representative. (MDR Art. 11(4); MDCG 2022-16, p. 3)

When a partner becomes the manufacturer. A distributor, importer or other person takes on the manufacturer's obligations if it makes a device available under its own name, registered trade name or registered trade mark. The exception is a distributor or importer that agrees with the manufacturer that the manufacturer stays named on the label and responsible. (MDR Art. 16(1); IVDR Art. 16(1))

The same applies to anyone who changes the intended purpose of a device already placed on the market or put into service. It also applies to anyone who modifies such a device in a way that may affect compliance. Translating the manufacturer's information and changing outer packaging are not such modifications, under the conditions of Article 16(2) to (4). (MDR Art. 16; IVDR Art. 16(1))

7. How the answer is reached#

The three answers depend on one another, in this order:

1. The intended purpose is settled first, because every later answer depends on it. It covers the label, the instructions, promotional and sales material and the clinical evaluation. (MDR Art. 2(12))
2. Qualification follows: device, IVD, accessory, Annex XVI product, or none. MDCG 2021-24 rev.1 recommends settling it before applying any classification rule. (MDR Art. 1, 2; IVDR Art. 1, 2; MDCG 2021-24 rev.1, p. 16)
3. Each component is classified separately, including software and accessories, under Sections 3.2 and 3.3 of Annex VIII. (MDR Annex VIII s. 3.2, 3.3)
4. Every plausible rule is tested, and the strictest that applies sets the class under Section 3.5. (MDR Annex VIII s. 3.5)
5. The route follows the class, from the table in section 4. (MDR Art. 52; IVDR Art. 48)
6. The roles follow from where the company is established and whose name its partners put on the label, as set out in section 6. (MDR Art. 11(1), 16(1))

A European classification has to be worked out afresh even where a US determination exists, because the input is the European intended purpose and the European rules. (MDR Art. 2(12); Annex VIII s. 3.1)

8. The four running cases#

The monitor: a wearable cardiac monitor from a US company#

Intended purpose (illustrative). The monitor records the wearer's heart rhythm continuously for later review by a clinician. A companion application displays the recording.

As illustrative assumptions, the monitor is already cleared and selling in the United States, it launches first in Germany and the Netherlands together and later in France, and the application runs on the patient's phone.

Section 3.7 treats a device as allowing direct diagnosis when it provides decisive information for the diagnosis. Our reading is that a rhythm recording made for a clinician's diagnosis gives such information, so the class IIa branch of Rule 10 is met. (MDR Annex VIII s. 3.7, Rule 10)

Rule 10 moves a monitoring device to class IIb where it is specifically intended for monitoring vital parameters whose variations could result in immediate danger. Cardiac performance is the rule's own example. (MDR Annex VIII, Rule 10)

MDCG 2021-24 rev.1 puts continuous surveillance in anaesthesia, intensive care or emergency care in class IIb, and routine or self-monitoring readings in class IIa. Our reading is that a recording reviewed after the event sits with the self-monitoring readings, so the hardware stays at class IIa. (MDCG 2021-24 rev.1, pp. 44 and 45)

For the application, MDCG 2019-11 rev.1 gives two neighbouring examples. Software obtaining readings of vital signals in routine or home monitoring is class IIa. A mobile app that analyses the heartbeat, detects abnormalities and informs a physician is class IIb, where the information is intended to guide the physician's diagnosis. (MDCG 2019-11 rev.1, p. 34)

The same guidance says monitoring software will in most circumstances fall under Rule 11's first paragraph. It treats the monitoring paragraph as a specific rule for software intended only for monitoring. (MDCG 2019-11 rev.1, p. 18)

Our reading is that the routine or home monitoring example is the closer match, because an application that only records is software intended only for monitoring. On the same reading, the worst harm that a decision taken on a later review of the recording could cause falls short of the class IIb threshold in Rule 11's first paragraph. That threshold is a serious deterioration of health or a surgical intervention. (MDR Annex VIII, Rule 11)

Whether the application will include any function that analyses the rhythm is the question to put to the notified body. On the guidance's example, an algorithm that analyses the rhythm and flags abnormalities to guide a physician's diagnosis would move the application to class IIb. (MDR Annex VIII, Rule 11; MDCG 2019-11 rev.1, p. 34)

The triage tool: AI-enabled software from a European company#

Intended purpose (illustrative). Triage nurses in adult urgent care centres use the software to suggest how soon each patient should be seen. It is used for patients the nurse has already assessed as having no life-threatening condition. The nurse confirms or changes the suggestion.

As illustrative assumptions, the company's home Member State and first market is Germany, and it sells the tool directly to hospitals as well as through an online app platform.

The class depends on the worst impact that a decision based on the tool's suggestion may have. Class IIb needs a decision that may cause a serious deterioration of health or a surgical intervention. Class III needs one that may cause death or an irreversible deterioration. (MDR Annex VIII, Rule 11)

MDCG 2019-11 rev.1 reproduces, for illustration, a risk table from the International Medical Device Regulators Forum. The table grades whether the information treats or diagnoses, drives clinical management, or informs it. In a serious situation it gives class IIa for driving or informing management and class IIb for treating or diagnosing. (MDCG 2019-11 rev.1, pp. 18 and 33)

Our reading is that a patient given too low a priority waits longer, and for some urgent conditions the wait may cause a serious deterioration. Class IIb is therefore the prudent planning assumption. Limiting use to patients assessed as having no life-threatening condition does not by itself rule out an irreversible deterioration, and whether one can occur is a clinical question for the evidence plan.

Whether the AI Act reaches the tool, and from when, is in chapter 10, Which AI and cybersecurity rules reach the product, and from when?.

The implant: a spinal implant from a European company with a directive certificate#

Product (illustrative). A spinal implant system made up of an interbody cage with screws, plates, hooks and rods.

As illustrative assumptions, the company sells the system in Germany and Italy under its directive certificate, has not yet entered France, and is seeking its first MDR certificate.

Rule 8 puts implantable and long-term surgically invasive devices in class IIb. It makes spinal disc replacements and implantable devices in contact with the spinal column class III, "with the exception of components such as screws, wedges, plates and instruments". The words "such as" leave room for components the list does not name, and the rule gives no answer on wires, pins or rods. (MDR Annex VIII, Rule 8)

MDCG 2021-24 rev.1 reads contact with the spinal column as intended contact with its bony structures. It treats hooks that fix rods as similar to the named components. (MDCG 2021-24 rev.1, p. 41)

A class III implant is subject to the clinical evaluation consultation procedure. The exemption for renewals applies only to certificates already issued under the MDR, so it does not help with a first MDR certificate. Our reading is that an unchanged legacy cage was not designed by modifying another device, so the modification exemption does not apply either. (MDR Art. 54(1), (2))

The Article 52(4) list of class IIb implants assessed per generic device group names screws, wedges, plates, wires, pins and spinal posterior fixations, among others. The list decides how the documentation is sampled and does not change the class. (MDR Art. 52(4); MDCG 2021-24 rev.1, p. 41)

A directive certificate counts under the transitional provisions only if it meets the conditions of Article 120(2) on when it was issued, whether it was still valid and whether it was withdrawn. Devices it covers may then be placed on the market or put into service, until the date Article 120(3a) sets for their class, only while the conditions of Article 120(3c) are met. The device must continue to comply with the directive, with no significant change in design or intended purpose and no unacceptable risk. (MDR Art. 120(2), (3a), (3c))

By deadlines in Article 120(3c), the manufacturer must also have put in place a quality management system under Article 10(9) of the MDR. The manufacturer or its authorised representative must also have lodged a formal application with a notified body and signed a written agreement with it. On the date the law in this chapter was checked, those deadlines had passed. They have been amended before, and the current consolidated text of the MDR, listed in the Sources, gives the dates in force. (MDR Art. 120(3c))

Under Article 120(3d), the MDR's requirements on post-market surveillance, market surveillance, vigilance and registration of economic operators and devices apply to these devices in place of the directive's. (MDR Art. 120(3d))

The near-patient test: a cardiac troponin test from a Swiss company#

Intended purpose (illustrative, two versions). Serial: health professionals use the test near emergency patients for serial measurement of cardiac troponin over time. It aids the diagnosis of an acute cardiac event and monitors cardiac muscle injury. Single: the same, for a single measurement, to aid the diagnosis of acute myocardial infarction.

As illustrative assumptions, the company also supplies the point-of-care analyser that reads the test, and already sells the test through distributors in Germany, the Netherlands, Belgium and Austria from its Swiss home market.

(IVDR Art. 2(2), 2(5), 2(6), 2(26), 2(27), 11, 48(7), (8), (9), 112; Annex VIII, Rules 3, 4, 6; Annex IX s. 5.1; MDCG 2020-16 rev.5, pp. 31, 32, 39; MDCG 2021-27 rev.1, p. 5)

Near-patient devices are classified in their own right under Rule 4(b), and MDCG 2020-16 rev.5 reads that as requiring every rule to be tested against the intended purpose. (IVDR Annex VIII, Rule 4; MDCG 2020-16 rev.5, p. 39)

Rule 3(j) puts in class C devices for monitoring levels of biological components where an erroneous result risks a patient management decision resulting in a life-threatening situation. MDCG 2020-16 rev.5 applies Rule 3(j) to serial measurement over time and names troponin used to help determine an acute cardiac event. It places a mobile version of such a test in class C. (IVDR Annex VIII, Rule 3; MDCG 2020-16 rev.5, pp. 31, 32 and 39)

Rule 3(j)'s own condition must also be met. Our reading is that a falsely normal result can send a patient with a myocardial infarction home, which is a life-threatening situation. (IVDR Annex VIII, Rule 3(j))

MDCG 2020-16 rev.5 also says Rule 3(j) does not apply to a single diagnostic measurement. It reads Rule 3(k), on the management of patients with a life-threatening condition, as applying to patients already diagnosed. With neither rule applying, the single-measurement test falls to class B under Rule 6, the default rule. (IVDR Annex VIII, Rules 3, 6; MDCG 2020-16 rev.5, pp. 31 and 33)

In the guidance's description, Rule 6 devices are those where an erroneous result is unlikely to put a person in immediate danger. The words of Rule 3(k) do not say "diagnosed". Our reading is that class B is contested on both grounds, so the single-measurement test is planned as class C until a notified body confirms otherwise. (IVDR Annex VIII, Rules 3, 6; MDCG 2020-16 rev.5, p. 43)

The class C answer depends on two phrases in the intended purpose: "serial measurement" and "monitor cardiac muscle injury". MDCG 2022-16 reads the regulation as requiring the Swiss company and its authorised representative each to have its own person responsible for regulatory compliance, and these must be two different people. (MDCG 2020-16 rev.5, p. 31; IVDR Art. 15(1), (6); MDCG 2022-16, p. 9)

9. When specialist help is worth paying for#

• The product sits on the device and medicine boundary, or acts by pharmacological, immunological or metabolic means. (MDR Art. 1(8), (9), 2(1))
• Software draws on IVD and device data together, where the test that decides which regulation applies comes from the guidance and calls for judgement. (MDCG 2019-11 rev.1, pp. 14 and 15)
• The class depends on which branch of Rule 11 applies, since the line between IIa, IIb and III rests on the impact that decisions based on the software may have. (MDR Annex VIII, Rule 11)
• The product is class III, implantable, or a companion diagnostic, where the routes add consultation steps. (MDR Art. 52(3), (4), 54(1); IVDR Art. 48(7))
• The company holds a certificate under the directives, where continued access to the market depends on meeting the conditions of Article 120. (MDR Art. 120(3a), (3c))
• A partner wants to sell under its own brand, or the company is outside the Union. (MDR Art. 11(1), 16(1))
• The notified body takes a different view of the class, before the company chooses whether to argue its case, redraft the claims, or refer the dispute to the competent authority. (MDR Art. 51(2); IVDR Art. 47(2))

Conclusion#

The three answers depend on one another and are reached in order, starting with the intended purpose, meaning what the manufacturer says the product is for. It is read from the label, the instructions, promotional material, and the clinical evaluation. It decides whether the product is a medical device or an in vitro diagnostic medical device (IVD), a test on samples taken from the body. The classification rules, applied to the same intended purpose, give the risk class, and where several rules apply, the highest class prevails.

The class sets the conformity assessment route, the procedure showing the device meets the regulation. It also decides whether a notified body, an assessment body designated under the regulations, takes part, which drives much of the cost and timing of entry. Who is responsible is decided separately, by which company places the product on the market under its own name and where that company is established.

Any change to the intended purpose means the qualification, class, and route must be worked out again. A classification made in the United States does not carry over, because it starts from the European intended purpose and rules.

In the four running cases, some answers rest on readings labelled as the authors' own ("our reading") or the guidance's. For the US company's wearable heart monitor, the hardware is class IIa on our reading. Its phone application is classified separately: class IIa if it only records for later review, and class IIb if it analyses the rhythm and flags abnormalities to guide a physician's diagnosis. Whether the application will analyse the rhythm is therefore the question to put to the notified body.

For the European company's AI-enabled triage software, Rule 11, the MDR's classification rule for software, makes classes IIa to III all arguable, and class IIb is the planning assumption. The tool would be class III if a wrong decision based on its suggestion may cause death or an irreversible deterioration of health. Limiting use to patients assessed as having no life-threatening condition does not by itself rule that out; that is a clinical question for the evidence plan.

For the European maker of a spinal implant system, the class differs by component. The interbody cage is class III, screws and plates are IIb, hooks are IIb on the guidance's reading, and the rule leaves rods, wires, and pins open. The cage needs a full assessment plus an extra consultation on its clinical evaluation, with no renewal exemption for a first MDR certificate. The system stays on the market under its certificate from the former directive only while the transitional conditions of Article 120 are met.

For the Swiss company's near-patient cardiac troponin test, the class turns on the wording of the intended purpose. It is class C for serial measurement. For a single measurement it is class B on the guidance's reading, which is contested, so both purposes are planned as class C until a notified body confirms otherwise. The company and its authorised representative in the Union each need their own person responsible for regulatory compliance; on the guidance's reading, these are two different people.

A notified body takes part for all four products.

Later chapters build on these answers. Chapter 5 covers the harmonised standards, and chapter 8 the choice of notified body and the work with it. Chapter 9 covers registration in the European database on medical devices (EUDAMED) and the unique device identifier (UDI), the code that identifies each device. Chapter 10 sets out what the AI Act adds for software such as the triage tool. Chapter 11 covers the obligations after launch, and chapter 12 whether Union health technology assessment reaches the product.