Deep splits have opened up within Labour on the question of law and order after a shadow cabinet minister said the party was no longer interested in appearing to be the toughest on crime.Baroness Chakrabati, the shadow attorney general, said in a radio interview that it was time to end the “authoritarian arms race in British politics” that she said had led to a doubling of the prison population.But her party colleague Lord Falconer, the former lord chancellor, said Labour would be punished by voters if it was seen to be supporting softer sentences for criminals.Lord Falconer said the electorate would not support cutting sentences for sexual, violent and drug-related offences which have made up the bulk of the increase in the prison population.He said public attitudes towards crime had led to the tougher rhetoric from politicians during the 1990s, when Tony Blair declared in opposition that Labour would be “tough on crime, tough on the causes of crime” and then-home secretary Michael Howard declared that “prison works”.In an interview on Radio 4’s Today programme Lady Chakrabarti, the former Liberty director, said: “In my adult lifetime I have seen a doubling of the prison population. I think this is caused by an authoritarian arms race in British politics, particularly between the two parties.”Shadow home secretary Diane Abbott described her comments as “great” and added: “Time to end the criminal justice arms race.”But Lord Falconer said the riots that have swept through several prisons in recent weeks were the result of staffing cuts rather than tougher sentences.”The prisons are in a mess because of the deliberate decision to reduce the number of prison officers while not reducing the prison population,” he said.The peer, who was Jeremy Corbyn’s shadow justice secretary until June, acknowledged that too many people were remanded in custody before trial, while some sentences were too long in non-violent, non-sexual cases.But he rejected any calls to cut sentences for more violent crimes.“I don’t think it’s right to think about reversing the increase in the severity of sentence that’s taken place over the last 25 years in relation to violence cases and sexual cases and drug cases – big drug-dealing cases,” he said.Lord Falconer told the Today programme on Saturday that the changes in sentence severity reflected the way society viewed the impact of crime.He said: “I think over these last 25 years, for example in relation to sexual crime, people have become much more aware of the extent of it, the damage it has done and they refuse to accept it, and that is reflected in the way that the criminal justice system has dealt with it.”If you call it an arms race, because both political parties reflected that debate, then that may be one way of looking at it. But I think a better way of looking at it is that society changed its attitude and became much tougher to those things.”I don’t think society would wish to go back to the position of 1993 or 1992 when, for example, sexual crimes were less prosecuted and sentences were much more lenient.”Lord Falconer added: “Two-thirds of the increase in the number of people in prison between 1993, when the prison population was 41,000 and now, when it’s 86,000, has been caused by increased numbers of peoples in for longer for sex, violence and drugs.”I don’t think that there should be a very significant change in relation to that.”John Spellar, Labour’s former Northern Ireland minister, described Lady Chakrabarti’s interview on Friday as a “car crash”.He added: “I think it will go down very badly in the country. Tony Blair’s doctrine of ‘tough on crime, tough on the causes of crime’ set a policy that got us back in line with the public and recognised their fear of anti-social behaviour, burglary, muggings and worse and indicated very clearly that we were on their side.” Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings.