What is ICH E6(R3), and when did it take effect?

Short answer

ICH E6(R3) is the current international Good Clinical Practice guideline. ICH adopted its principles and Annex 1 on 6 January 2025. They came into effect in the EU on 23 July 2025, and FDA published them as final guidance in September 2025. Annex 2 comes into effect in the EU on 15 January 2027.

Why

E6(R3) has three parts. The principles apply to every trial. Annex 1 explains how to apply them and replaces E6(R2).

Annex 2 covers pragmatic and decentralized trials and trials that use real world data. ICH adopted Annex 2 on 3 June 2026, and EMA's scientific committee adopted it on 25 June 2026. The revision is not a list of new forms.

It asks for quality built into the design, a focus on the factors critical to quality, and controls proportionate to risk. It also adds a section on data governance, covering audit trails, data corrections and computerised systems. The legal weight differs by region.

In the EU, the Clinical Trials Regulation makes GCP a legal duty and EMA applies E6(R3) as its GCP guideline. In the US, FDA guidance is not binding, while the regulations in 21 CFR parts 50, 56 and 312 are. A guideline also never overrides a hard legal rule.

The EU 7 day deadline for reporting a serious breach still comes from the Regulation, not from E6(R3).

A strong answer covers

Principles, Annex 1 and Annex 2 as three parts
ICH adoption 6 January 2025 and EU effect 23 July 2025
FDA final guidance in September 2025, nonbinding in the US
Annex 2 on decentralized and pragmatic trials, EU effect 15 January 2027
Shift to quality by design and proportionate risk control

Common mistakes

Calling E6(R3) a draft or saying E6(R2) is still the current EU standard.
Assuming one effective date applies in every region, when FDA guidance and EU law work differently.
Describing R3 as more paperwork, when its main message is proportionality.

The interviewer might ask next

Which part of E6(R3) would change your day to day work most, and why?