How is a public inquiry structured?

23rd November 2022

In this second article focusing on public inquiries, we compare the different approaches and structures that have been adopted by public inquiries.

The structure of a public inquiry will have an impact on the way it is conducted, to ensure that the process is robust and efficient. This will maintain public and institutional confidence in the process and maximise the likelihood of its conclusions being followed.

Modules v Phases

The two more common categories for an inquiry structure are a modular approach and a phased approach. A modular approach is generally used when matters being investigated are sufficiently discrete to allow them to be considered separately from each other. Each module runs separately but may have common themes running through them. Modules can also be run sequentially with preparations for each module being run simultaneously. This ensures expedition and also ensures that participants only get involved when the module is relevant to them.

A phased approach is generally used when topics are inextricably linked to one another and therefore cannot be easily or neatly separated. Such an approach is usually divided into sub-sections that are referred to as phases. However, these phases are run sequentially as one long investigation, and participants are likely to remain involved at all stages.


The decisions taken by an inquiry about its process will have considerable implications for participants in terms of time and cost.

For example, the Independent Inquiry into Child Sexual Abuse took a modular approach and each module focused on a different institution, for example Rochdale Council, or topic, for example, child sexual exploitation and the internet.

This allowed those taking part to only be involved on parts relevant to them thereby ensuring that they only dealt with evidence in relation to those modules or topics, making the disclosure process more streamlined and cost-effective.

Unlike the Independent Inquiry into Child Sexual Abuse, the Grenfell Tower Inquiry is being run as a single inquiry, structured into two phases. The consequence of this is that participants must be involved for longer and receive and hear evidence called by the inquiry, even if it does not directly concern them. However, the issues in this inquiry are more confined and the main participants are likely to need to remain involved throughout.

The UK COVID-19 Inquiry is following a modular approach due to the scale of its scope. It will be running a series of hearings and making interim recommendations based on the subject-matter of each module.

We have also looked at involvement in a public inquiry the process to become a core participant here and an overview of an inquiry here.

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