MICHAEL Howard's "stupidity" in abolishing the unconditional right to silence is demonstrated by The Lawyer's investigation into the new law, according to Labour.
But the Government has defended the law despite concern from opposition parties over the findings of last week's survey of criminal law solicitors.
"If someone is innocent what have they got to hide," said a Home Office spokeswoman.
She said "careful consideration" had been given to the new law, adding: "Our point is that it is as much a miscarriage of justice if someone who is guilty goes free as when someone who is innocent is convicted."
More than half the police station advisers questioned in The Lawyer's poll of 204 solicitors said the chances of miscarriages of justice had increased with the abolition of the unconditional right to silence.
Labour's shadow deputy home secretary Alun Michael said: "This survey vindicates the reservations we expressed and demonstrates the stupidity of the Home Secretary in not listening to what we said."
He said a series of sensible amendments to safeguard the vulnerable had been rejected by the Conservatives during the passage of the Criminal Justice Act and Labour "would have to look very closely to see what could be done".
Liberal Democrat home affairs spokesman Alan Beith said the findings, in which more than one in five lawyers claimed the change had made no difference to their tendency to advise silence, appeared to back up his fears that "the change would have little impact on those it intended to deal with, the experienced criminal who has already worked out what he is going to say".
The police have claimed "differences in perception and judgement" between police officers and lawyers were to blame for the fact 11 per cent of the poll described the police as unco-operative.
David Blakey, secretary of the Association of Chief Police Officers, said: "We are very pleased that two thirds of the lawyers on this limited survey think that the quality of pre-interview disclosure has improved since the change in the law."