Public interest immunity (PII) is a doctrine utilized in British common law when it is believed that the disclosure of certain information could be detrimental to public safety. When a PII request is filled out, it is reviewed by the court, and the court can issue an order that the information not be disclosed. PII requests are usually submitted by government ministers although there can be other circumstances in which they may be used.
This doctrine must balance two conflicting needs. It is generally accepted that when a case is tried in court, both sides should have access to all information pertaining to the case so that the case can proceed fairly. In a process known as legal discovery, information is shared so that both sides have an opportunity to prepare. This is especially important in criminal cases where evidence can be used to convict someone of a very serious crime, and thus that person should have access to that evidence for examination and study.
However, certain kinds of evidence can pose a threat to public safety. Releasing information might compromise national security, expose police methods and make it hard for to police to work, or threaten the safety of children. Likewise, identities of informants and sources are also deemed worthy of protection. In these cases, a public interest immunity request may be filed to prevent the disclosure of the evidence.
The court must weigh a public interest immunity filing carefully. Courts do not want to threaten the health and safety of the public by allowing sensitive information to get out, but they also do not want to deprive people of due process in a court of law. If the request is granted, the side which has sensitive information is barred from exposing it to the other. In some cases, the court may also determine that a case should be held behind closed doors for safety reasons so that sensitive information cannot be released to the public.
Sometimes known as Crown privilege, this legal doctrine has attracted controversy. There have been accusations that ministers have abused public interest immunity in order to suppress potentially damaging or embarrassing information which is not necessarily a threat to the public. Likewise, some critics have argued that the use of public interest immunity to suppress materials used during investigations is unfair to the person being investigated, as it is difficult to challenge the results of an investigation when the methods are not known.
