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The role that harmonised standards play in demonstrating compliance with the requirements of EC Medical Device Directives is highlighted in this article. The article outlines the legal and practical implications for manufacturers.


The use of harmonised standards in the conformity assessment process leading to CE marking of medical devices and in vitro diagnostic medical devices has been given recent prominence by a number of relatively high profile challenges from both manufacturers and the European Commission (EC). These challenges have involved a range of standards including EN 60601-1:2006 Media discussion on the topic has generated some confusion on the issues. This article seeks to set out a more objective analysis of the situation and highlight that in fact, nothing has changed.

Directive references

To ensure the basis for the use of European harmonised standards and equivalent European documents is understood, it is worthwhile to first review the major references in the two directives under discussion. It can be considered that the approach taken in the Active Implantable Medical Device Directive is completely analogous to Directive 93/42/EEC for Medical Devices, and that the In Vitro Diagnostic Medical Device Directive 98/79/EC has equivalent wording but with the additions as stated below:

  • Directive 93/42/EEC Article 3 states: ‘The devices must meet the Essential Requirements set out in Annex I which apply to them, taking account of the intended purpose of the devices concerned.’ This represents the fundamental and overriding principle of CE conformity and applies in particular to the first clause of Essential Requirement 2.
  • Essential Requirement 2 states: ‘The solutions adopted by the manufacturer for the design and construction of the devices must conform to safety principles, taking account of the generally acknowledged state-of-the-art.’ This means documents and standards that are safety related, relevant to the intended purpose and considered state-of-the-art must be taken into account and solutions adopted that are identical or conform to the same safety principles.
  • Directive 93/42/EEC Article 5 states: ‘Member States shall presume compliance with the Essential Requirements referred to in Article 3 in respect of the devices which are in conformity with the relevant national standards adopted pursuant to the harmonised standards the references of which have been published in the Official Journal of the European Communities.’ The Directive additionally describes some cases where the European Pharmacopoeia may be seen as equivalent to harmonised standards.
  • Directive 98/79/EC additionally states in Article 5: ‘Member States shall presume compliance with the Essential Requirements referred to in Article 3 in respect of devices designed and manufactured in conformity with common technical specifications drawn up for the devices in List A if Annex II and, where necessary, the devices in List B of Annex II. […] Manufacturers shall as a general rule be required to comply with the common technical specifications; if for duly justified reasons manufacturers do not comply with those specifications they must adopt solutions of a level at least equivalent thereto.’

Unlike some other regulatory jurisdictions European Medical Device Directives do not make the use of specific standards mandatory, with the exception of the use of common technical specifications for certain IVD devices.

Harmonised standards and Annex Z

It is the policy of the European standards bodies CEN and CENELEC to adopt international ISO and IEC standards where possible and so most harmonised standards are dual ISO or IEC standards. All harmonised standards will contain an Annex Z for each EC Directive under which they are harmonised and, in this respect, they are not identical to the ISO or IEC version.

Annex Z is in the form of a table correlating the requirements in the standard with the Essential Requirements where compliance can be presumed. Manufacturers cannot use harmonised standards to claim compliance using a presumption of conformity where no such correlation is shown in Annex Z. Unfortunately, in the last few years many of the Annex Zs have been shown to be inaccurate or over simplistic indicating a degree of correlation which cannot be justified.

CEN and CENELEC are in the process of reviewing the standards and reissuing them with more accurate Annex Zs. Most EN standards published since the beginning of 2012 will have accurate and more detailed Annex Zs, and these can be relied on by manufacturers to indicate precisely the Essential Requirements where compliance can be presumed. Earlier dated standards are still valuable but the extent of the compliance may be exaggerated and further justification of compliance with indicated Essential Requirements may be required.

It should be noted that very few harmonised standards can be considered a presumption of compliance with all the essential requirements, so harmonised standards should be seen by manufacturers as just part of the requirements to be met for CE marking. Where the harmonised standard is an EN ISO standard the requirements will be identical to the ISO version, but without knowledge of the contents of the Annex Z manufacturers will not be able to make precise claims of a presumption of conformity in their technical documentation.

New or revised harmonised standards

Some of the recent media discussion has indicated that Europe operates a system of product grandfathering, whereby designs already approved and in compliance with previous standards or previous versions of standards are exempt from further testing. This is not the system adopted by Europe. While it is true that devices already physically placed on the market are not affected by new or changed standards, unless they have been shown to be unsafe, all products at the time of being placed on the market must meet all Essential Requirements (including Essential Requirement 2). As a result, manufacturers must take account of the current state-of-the-art with respect to safety, which may now be represented by the new or changed standard.

When a harmonised standard is revised or is replaced there is a ‘date of cessation of presumption of conformity of the superseded standard’, which is an important date for all manufacturers who have used the superseded standard as a presumption of conformity. This date is when their previous justifications become invalid and without review or retesting their technical file will not adequately demonstrate conformity to the Essential Requirements.

In practice, a revised standard may not require full device retesting or process revalidation, this is because many standard revisions are only partial revisions. An approach for some manufacturers is to undertake a gap analysis between the obsolete version and the revised harmonised standard. If this documented analysis shows that the changes in the standard are not relevant to the device in question, or could have no effect upon their device, then retesting to the new standard is not required. Alternatively, and more commonly, this analysis could demonstrate that only partial retesting is required (this may be appropriate for some devices in relation to EN 60601-1). This fully documented analysis and rationale must form part of the technical file for the device.

Options for the use of harmonised standards

Many harmonised standards represent the state-of-the-art or the international benchmark for safety, and in some cases for performance, and the market will have expectations of conformance. Therefore conformance to the appropriate harmonised standards, unless they have been generally judged inadequate, is for most manufacturers the easiest, clearest and in many cases the cheapest approach. The exception would be for innovative products for which the standards cannot meaningfully be applied. In these cases, the manufacturer is required to demonstrate conformance directly against the Essential Requirements. This normally involves extensive documentation and a lengthy review by the Notified Body against the basic principles of the Essential Requirements.

Where a manufacturer has chosen not to apply a harmonised standard (generally acknowledged to be state-of-the-art) for a safety aspect then this approach is acceptable. However, once again this normally involves extensive documentation and a lengthy review by the Notified Body against the basic principles of the Essential Requirements. The documentation must contain justification that equivalence to the safety principles of the harmonised standard has been demonstrated or that the safety principles cannot be applied to this type of device Where the harmonised standard contains non-safety related performance criteria, manufacturers have more flexibility to justify their non-application for the intended use; as harmonised standards are not mandatory and state-of-the-art applies to safety aspects only. For most manufacturers, the market expects conformance to standard performance criteria and so deviations should be considered only in exceptional circumstances, and where a definite benefit to risk ratio can be demonstrated.

Common technical standards, where they exist, for IVD devices fall into a different category and in effect must be applied.


All manufacturers should be aware of the current and imminent harmonised standards for devices they wish to place on the European market. These must be considered as one of the design inputs and references in their technical documentation. For the majority of devices and manufacturers, conformance to the appropriate harmonised standards is a cost-effective approach to conformity assessment and the European market, and conformance is encouraged.

Manufacturers should be aware that harmonised standards do not cover all aspects of a device. They can sometimes be behind the state-of-the-art, meaning manufacturers should be aware of all other standards, guidance and documents that are acknowledged to represent the state-of-the-art with respect to safety and performance. These also need be used as a means of demonstrating compliance to the Essential Requirements.
Europe wishes to encourage innovation and novel medical devices and so harmonised standards are not mandatory, with the exception of common technical specifications and those related to colour coding and symbols where deviations would be immediately dangerous. In the cases where harmonised standards are not used, manufacturers should expect to document the justification and data on which judgements are made to a high degree. This is because judgements will be examined and challenged by the Notified Body as no presumption of compliance can be assumed.

Further Information

A list of current harmonised standards and their applicable dates can be found here.