When the law is broken, particularly when someone is unlawfully killed, it is the duty of the state – the government and its agencies – to investigate and bring the perpetrator to justice. That is usually the job of the criminal justice system including the police, the prosecution service and the courts. When, however, there are credible allegations that servants of the state itself were involved somehow in a killing, an alternative to the normal criminal justice process may often be necessary.

There are three good reasons why special processes to investigate possible state involvement in unlawful killings are necessary.

First, although the damage to the victim is the same, the damage to the rule of law is much more serious if the perpetrator or abettor of a crime is a police officer or other state servant. Breach of law by those mandated to uphold and implement the law clearly weakens the rule of law itself. Public confidence will be reduced and people will be less willing to cooperate with a legal system that appears to practice collusion.

Second, the criminal law and investigative processes led by the police are there to deal with the actions of criminals. If the alleged perpetrator is a police officer or soldier – and particularly where the allegation is of organised and sanctioned criminality within these forces – these processes are likely to be less than effective. It is unlikely to be possible for a state agency to impartially and effectively investigate itself. There needs to be an independent and transparent process.

Finally, the state endures. It is to be hoped that criminal gangs and armed groups will, at some point, go away. The state, however, is always with us. If wrongdoing today or in the past is not exposed and dealt with, there is a continuing risk that it will occur again in the future. Furthermore, unfinished business in terms of allegations of past illegalities is bound to affect confidence and trust in the future.

Upholding the rule of law will therefore sometimes require special measures or inquiries to deal with allegations of collusion with wrongdoing by government and its agencies. The aim is not to privilege one set of victims over another, but to ensure that the rule of law offers its impartial protection to all people equally and that perpetrators will be brought to justice, whoever they may be. The criminal justice system will not always be successful in identifying and bringing to justice perpetrators and nor will special inquiries into state collusion, but both are necessary for a rule of law that protects the human rights of all.