17/03/2016 15:05 GMT | Updated 18/03/2017 05:12 GMT

The Tories Are Risking Decades of Progress in Policing

Life on Mars, a cop drama set in the 1970s, displayed a fictional portrayal of a British police station in which racism was endemic. Although fictional the drama was so accurate that it brought back chilling memories of my experience as a police constable at that time. Any black driver who was evasive or uncooperative was routinely arrested for being "a suspected over-stayer", an illegal immigrant. Such was the damage these arrests were causing to police relations with the black community that a policy decision was made that the police would no longer actively seek to enforce immigration law but would assist immigration officers when they needed it. That was decades ago.

This week, after years of progress, the Conservative government's Immigration Bill, currently going through the House of Lords, contains some draconian new powers and new criminal offences. Amongst them is a new criminal offence of driving when unlawfully in the United Kingdom and powers to search an individual, a vehicle and a driver's home address, without warrant, for a driving licence. The police gave-up going out looking for immigration offences decades ago because of the detrimental effect it was having on police community relations. This new legislation puts the police back on the front line in looking for illegal immigrants and the consequences for race relations could be damaging.

Clearly if someone is arrested for a criminal offence and there is a suspicion that they may be illegally in the country, the police should and do inform the Home Office and immigration officers investigate. This new offence puts the police back in the position of having to actively enforce immigration law. Who else but the police are going to arrest people for driving when unlawfully in the UK? Not only that, but if they suspect someone to be an illegal immigrant, they can search them, their car and their home address for a driving licence.

In a 2014 Her Majesty's Inspectorate of Constabulary survey of motorists, almost twice as many black drivers said they had been stopped by the police than white drivers. The black drivers were more likely to be given no explanation for being stopped and were less likely to be arrested or prosecuted for any offence. Stops under the Road Traffic Act are not recorded so we only have the survey to go on but 'stop and search' by the police is recorded. Despite an improvement in recent years, you are still over four times more likely to be stopped and searched by the police if you are black than if you are white. How much more disproportionate is it going to be when the police are specifically looking for illegal immigrants under this new legislation?

Fear not, the government say, we have made it very clear that people should not be stopped on the basis of their race or ethnicity and anyway it won't happen because it would be unlawful under the Equalities Act. The Home Secretary has made it abundantly clear to the police that racial profiling is wrong but if you are still 4.2 times more likely stopped and searched, and twice as likely to be stopped in your car if you are black than if you are white, you have to ask how effective ministerial edicts and the Equalities Act have been. The government say the new powers will only be used when the police stop someone for "an objective reason". The HMIC survey suggests the police already stop black drivers for no objective reason.

Liberal Democrats want effective border security to prevent illegal immigrants from coming to the UK in the first place, effective exit checks so we know when someone has overstayed their visa and an effective immigration service that tracks down over-stayers and others who are working in the UK illegally. The police have already suffered significant cuts to their budgets and community policing has been hit hard. They have a frontline role in liaising with communities to build the kind of trust and confidence that leads to vital information about serious crime and terrorism being passed on to them by the public. Anything that is likely to put them into conflict with the public and black and minority ethnic communities in particular, is going to make us all less safe. That is exactly what this legislation is likely to do. After decades of progress the Tories now risk turning the clock back.

Lord Paddick is a Lib Dem peer and party home affairs spokesman, and a former Met Police commander