Police Chiefs' blog: CC Sara Thornton - we must investigate and disclose all reasonable lines of inquiry while guarding against intrusion

We swear an oath when we become a police officer -  to always act with fairness and impartiality.  That principle must be at the heart of our investigations, and is absolutely connected to the Attorney General’s guidance that sets out police officers’ duty to pursue all reasonable lines of inquiry – those that lead towards the suspect and those that lead away. 

In recent months we have been working with Crown Prosecution Service (CPS) to address the flaws in recent cases, and we now have a good joint plan that we’re all behind.  It’s become clear that the key is identifying the reasonable lines of inquiry early with the CPS, and if it at all possible with the defence, which then guides what needs to be disclosed.  This addresses the cultural problem, set out by our disclosure lead Chief Constable Nick Ephgrave, where officers see disclosure as an administrative task at the end of the process rather than being integral from the beginning. 

Investigation and appropriate disclosure is as old as policing but we are challenged by sheer volume of data we all hold in 2018, and therefore the many, many more potential lines of inquiry.  So, we must cooperate, acting with fairness and impartiality, and this might mean practical conversations with complainants and suspects at the start of the process to ask them “is there anything in your phone that’s relevant to the case?” 

In the desire to solve this issue, we must guard against going beyond reasonable lines of inquiry.  We cannot allow people to be put off reporting to us because they fear intrusion into their lives and private information that’s not relevant to the crime being shared in court –the digital equivalent of the tired trope of women in short skirts “asking for it." This is why the idea of handing all the unused material to the defence won’t work – it would go beyond what is reasonable and proportionate.

Getting this right means we are asking investigators to do more at a time when we have a shortage of detectives and many other complex demands.  We must be honest that this may slow investigations in the short term and forces will have to consider moving resources - as the Metropolitan Commissioner Cressida Dick said last week.

Longer term, if technology is the challenge, it’s also got to be part of the solution.  So with the CPS we have set up a group to explore the clever tech that could help us – whether it’s machine learning or artificial intelligence. 

New technology, adequate numbers of investigators, effective joint working with prosecutors and the right mind-set all need to be part of our response to recent failed cases. The integrity of the criminal justice system depends upon us making improvements.

National Police Chief’s Council Chair Sara Thornton