Opting out of European Union law-and-order measures could jeopardise the UK’s ability to fight cross-border crime, the Law Society has warned.

Its warning comes as a House of Lords Committee began taking evidence on the opt-out, which is likely to be announced by the government before next year.

Meanwhile, a group of Conservative backbench MPs said Britain should opt out ‘to retain national democratic accountability over such a vital area of policy and lawmaking, and preserve the distinctive common law tradition so important in the UK justice system’.

The recommendation appears in a report by the Fresh Start group, which wants the UK to remain in the EU, but with ‘significant revisions’ to treaties.

In original negotiations for the 2009 treaty, which amended the two treaties that formed the constitutional basis of the EU, the Labour government negotiated an opt-out for the UK on 130 measures designed to ease cross-border cooperation on crime and justice issues. The UK has to decide whether to accept or decline the entire package.

Measures at issue include the European arrest warrant, membership of the EU's judicial and policing organisations Europol and Eurojust, as well as arrangements to share databases of criminals and DNA between member states.

The final decision on what the UK does will be taken in May next year. Responsibility for European-wide policing and crime prevention measures will pass to the European Court of Justice from December 2014.

Last autumn home secretary Theresa May said that the government intended to follow the previous government’s lead, and opt out of the arrangements made prior to the Lisbon Treaty. The UK will remain bound by EU criminal justice measures agreed after the Lisbon Treaty.

If it chooses to opt out, it can at a later date try and opt back in to individual measures - if the rest of the member states agree.

Giving evidence to the Lords EU subcommittee on Justice, Institutions and Consumer Protection today, Richard Atkinson, chair of the Society’s criminal law committee, warned against ditching measures that help cross-border co-operation. ‘Systems need to be in place to facilitate effective cross-border co-operation in criminal justice matters between member states and provide for corresponding procedural rights for victims and suspects.’

He added: ‘We can see no reason for opting out of measures, which on anyone's analysis are not harmful, and a good number of which are beneficial and which we will need to opt back into at potentially great cost to the taxpayers of this country.’

Atkinson said stepping away from the European arrest warrant would be ‘detrimental’ as it could leave suspects being held in pre-trial detention for longer periods.

He also questioned the implications for the UK’s involvement with Eurojust if the UK withdraws from the measures.