Plans to give British police the power to retain fingerprints and other samples from arrested suspects have been protested by both lawyers and human rights activists.
Under current law, police can only take such samples from suspects once they have been charged with a crime.
But under new Home Office proposals they will be able to take fingerprints and DNA from anyone they arrest, a move which has been highly criticized by the legal profession's Bar Council.
A spokesman for the Bar Council said the idea that somebody released without charge could end up on a register of criminals is frightening.
Human rights group Liberty said the measures would treat everyone who has ever been wrongly arrested as guilty by implication and could lead to wrong convictions based on DNA evidence alone, which has happened in the United States.
Ministers disagree and say the change in law would allow police to verify an arrested person's identity, preventing people who are wanted for earlier crimes from slipping through their grasp by giving a false name and address.