A government-sponsored review of possible racial bias in the criminal justice system must not be jeopardised by evidential shortcomings, the Bar Council and Criminal Bar Association have said.

Earlier this year prime minister David Cameron invited Labour MP and barrister David Lammy (pictured) to investigate evidence of possible bias against black defendants and other ethnic minorities in the criminal justice system.

In a joint response to Lammy’s call for evidence, the Bar Council and CBA said statistics used in formulating the review had their own shortcomings and limitations, and prohibited a comprehensive empirical analysis.

‘This issue is of too great a significance to risk being criticised for a lack of supporting evidence and in particular for not comparing “like for like” situations,’ the joint response states.

Some of the data the consultation document relies on appears to be contradictory, the Bar Council and CBA said.

For instance, one question states that BAME defendants are more likely to be acquitted while another question states that BAME defendants are more likely to be convicted.

The response also notes the lack of reference to arrest rates or previous convictions in the analysis.

It states: ‘If black defendants have on average more previous convictions, or are charged with more serious offences then it is not surprising that they are more likely to get remanded. Focus then needs to look at why they have more previous/more serious offences.

‘If, however, white defendants charged with similar previous and similar offences are consistently getting bail when black defendants are not, then a properly identifiable issue has been raised at that stage in the proceedings and ways can be found to address it.’

The Bar Council and CBA recommend that analysis be conducted between individuals with similar offending records at each stage of the criminal justice system – from arrest, through charging decision, arraignment, trial, verdict, sentence and reoffending.

‘We can then see the extent to which racial bias may or may not affect the decisions at each step. Only then can we seek to find ways to address this and minimise it,’ the response states.

Lammy is advised to concentrate research on one specific offence or group of offences to make the task of comparing like with like easier.

The Bar Council and CBA also recommend that immigration status and nationality, religious belief and the experience of those in the travelling community are considered in any analysis for it to be meaningful.

Interim findings from Lammy’s review are expected to be published in September or October. Recommendations will be made in spring 2017.