A planned EU-wide scheme that will make it easier for the police forces of member states to share evidence in their fight against international crime could have ‘grave implications’ for civil liberties, lawyers have warned.

Home secretary Theresa May announced last week that the government would support the new European Investigation Order (EIO). The scheme would cut delays by setting tight deadlines for evidence to be sent from one country to another.

However, lawyers warned that there are no agreed ­standards across Europe for pre-trial evidence gathering and analysis, no agreed procedural safeguards, and there is no coherent data protection regime. They claimed the EIO could disadvantage the defence in favour of the ­prosecution, and called on the government to make an impact assessment into the effects of the new scheme before signing up.

Jago Russell, chief executive of Fair Trials International, said: ‘The EIO has been pushed forward without debate at EU or domestic level. Even the most basic question – is this new law needed? – remains unanswered, with many EU countries, including the UK, saying the current system works well.

‘If we do not include safeguards in the legislation, we will be stuck with a justice measure which, like its predecessor, the European Arrest Warrant, which has seen citizens extradited for trivial and unproven offences, will result in serious cases of injustice and huge burdens on police time.’

Law Society president Linda Lee said the EIO should be restricted to more serious crimes, as using it for minor offences would ‘not be the best use of taxpayer’s money’. She added that defendants must enjoy ‘equality of arms’ with the prosecution.