# Clinical trials for medicines: Declaration of Helsinki and Clinical Trial Regulations alignment

Source: https://www.keypedia.com/records/uk_mhra_guidance/uk-mhra/a585f91a-7250-49fe-a9e1-50e116b9abde
Type: Guidance
Published: January 12, 2026
Updated: April 27, 2026

> The Medicines and Healthcare products Regulatory Agency (MHRA) has finalized updated guidance regarding the amended Clinical Trials Regulations, which reached full implementation on April 28, 2026. This regulatory framework establishes the legal requirements for conducting clinical trials within the United Kingdom, specifically emphasizing the role of the Declaration of Helsinki in trial ethics. A significant change in this update is the removal of references to specific versions of the Declaration; instead, trial sponsors are required to adhere to its general principles. The primary issue addressed is the potential for conflicts between these international ethical principles and the specific mandates of UK law. The guidance clarifies that while the principles of the Declaration of Helsinki are mandatory, they must not supersede the amended Regulations. In instances where a conflict exists, the MHRA requires sponsors to prioritize compliance with UK legislation. To ensure regulatory transparency, sponsors must take formal action by documenting the rationale for any deviations from the Declaration and evaluating the impact of these deviations on the trial. This ensures that clinical research remains ethically sound while strictly adhering to the updated national legal standards.

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## Content

The amended Clinical Trials Regulations took full effect on 28 April 2026. As such, this guidance should now be considered effective and is no longer in draft. This guidance explains that compliance with the principles of the Declaration of Helsinki is required by the amendment of the Clinical Trials Regulation but that reference to a specific version of the Declaration is no longer stated. The Regulations require that the principles of the Declaration of Helsinki must be complied with for all clinical trials except where this contravenes the requirements of the amended Regulations and examples of potential conflicts are given. Where a conflict arises the MHRA expects sponsors to prioritise compliance with UK law while documenting the rationale for deviation and any associated impact.

## Attachments

- [Declaration of Helsinki and Clinical Trial Regulations alignment](/government/publications/clinical-trials-for-medicines-declaration-of-helsinki-and-clinical-trial-regulations-alignment/declaration-of-helsinki-and-clinical-trial-regulations-alignment)