How Standards Become Harmonised Under EU Law: A Practical Guide

How Standards Become Harmonised Under EU Law: A Practical Guide

Most medical device and in vitro diagnostic device manufacturers already rely on established international standards. Quality management, risk management, software lifecycle and clinical investigation standards are often embedded in organizational processes long before EU regulations apply. Harmonisation under EU law is therefore primarily about whether existing standards can formally support regulatory compliance, rather than creating new documents.

This article explains how that process works, what changes when a standard is harmonised, and how manufacturers deal with limitations in coverage.

Existing standards as the starting point

The International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC) develop and publish international standards, which are used to define and determine consistency and reliability across many goods and services.

Standards such as ISO 13485 (Medical devices — Quality management systems — Requirements for regulatory purposes), ISO 14971 (Medical devices — Application of risk management to medical devices), and IEC 62304 (Medical device software — Software life cycle processes) were developed through international consensus. They represent recognized industry practice and are typically considered technical state of the art. In the writing of these standards consideration was given to the ability to meet EU legal texts.

Foundational process standards such as these are harmonised and are of general relevance to conformity assessment. Conformity with regulations is normally established within the processes specified by these fundamental horizontal standards.

When EU regulations such as Regulation (EU) 2017/745 and Regulation (EU) 2017/746 apply, the European Commission reviews whether these existing standards could support manufacturers in meeting the General Safety and Performance Requirements (GSPRs). If a standard is considered potentially suitable, the harmonisation pathway begins.

Standardization requests and alignment

To progress harmonisation, the European Commission issues a standardisation request to the European Committee for Standardization (CEN) or European Committee for Electrotechnical Standardization (CENELEC), as applicable. This request identifies which legal requirements the standard is expected to address.

Existing standards often require revision or amendments before harmonisation is possible. For example:

• The A11:2021 amendment of the European standard EN ISO 14791 was cited as a harmonised standard in 2022 in support of the European regulations.
• IEC 62304 was updated in 2021 with one amendment, with a view to addressing changes in software development practices and regulatory focus on software-based medical devices.
• ISO 14155 has been revised to align with clinical evidence requirements.

Revisions and amendments to a standard follow the standard development process and involve broad stakeholder input. The stakeholder input process requires consensus from the voting ISO or IEC members before revisions or amendments are published. The primary aim is to specify good scientific and technical practices along with aiming to align with regulatory objectives, not reinterpretation of legislation.

From European adoption to Official Journal of the European Union (OJEU) citation

International standards can sometimes be identified early in their development as potential candidates for harmonisation with EU legislation. For example, standards under development such as ISO 18969 on clinical evaluation may be considered for future regulatory use.

When an international standard is adopted by the European standards organisations, it is published as a European standard (EN). At this stage, the standard may be assessed against the requirements set out in the relevant European Commission standardisation request to determine whether it adequately supports the legislation.

However, a standard only provides presumption of conformity once its reference has been published in the OJEU. This citation formally recognises the standard as a harmonised standard under the relevant EU legislation.

What harmonisation changes in practice

Harmonisation does not change what the standard requires. It changes how it is recognised under EU law.

When harmonised standards such as EN ISO 13485:2016+A11:2021 are correctly applied, product-specific manufacturers may benefit from presumption of conformity with the specific regulatory requirements covered by the standard. This presumption is limited to:

• the cited version of the standard;
• the clauses that address specific legal requirements; and
• correct and complete application.

Manufacturers remain responsible for demonstrating overall conformity.

Managing gaps and partial coverage

No harmonised standard covers all EU regulatory requirements. For example, EN 62366-1(Medical devices — Part 1: Application of usability engineering to medical devices) provides a presumption of conformity for usability engineering processes aimed at reducing use-related risks, but it does not address broader regulatory obligations.

Where coverage is incomplete or harmonisation is not yet in place, manufacturers commonly rely on other standards, technical specifications, or documented internal approaches based on the state of the art. These approaches remain valid but are assessed without presumption of conformity.

Understanding how standards become harmonised helps organizations track regulatory status, avoid reliance on outdated citations, and build robust conformity strategies under EU law.