In addition to the formal scientific and medical assessment, the final decision is based on the operational implications of water cannon.
In August 2014, the Home Secretary wrote to a number of senior serving and former chief constables in order to gain a better understanding of the operational context in which water cannon could be used. These included the chief constables for major metropolitan forces, national policing leads, and the Police Service of Northern Ireland, where the use of water cannon has been authorised for some time.
The Home Office’s rationale is to be as transparent as possible in providing the background documents that informed the Home Secretary’s decision. However some sensitive information has been redacted to protect personal details and commercial interests and to avoid prejudicing the ability of the police to enforce the law. As a general principle, information has been redacted where it would be exempt from disclosure under the Freedom of Information Act, should a request for it be received.