Opposition parties sharply criticised the Criminal Justice Bill (No 2) introduced in the Dail by the Minister for Justice, Mr O'Donoghue.

Fine Gael's justice spokesman, Mr Jim Higgins, said it was the "most flawed and unnecessary piece of legislation" to come before the House in years.

Labour's spokesman, Mr Pat Upton, said it was fundamentally flawed and could prove decisive in some cases but useless in others involving serious crime.

Democratic Left's justice spokeswoman, Ms Liz McManus, described its approach as "nonsensical". She said the Bill was being used "to shore up the reputation of a Minister who is incapable of dealing with the issues already facing him".

But the Minister said it represented a "major piece of criminal law reform". He asserted there was a high level of public support for the measures in the legislation which included a minimum imprisonment of 10 years for people trafficking in drugs valued at £10,000 or more.

Trials would take place more quickly because of the abolition of preliminary examinations and courts would automatically inquire into the assets of convicted drug traffickers with the aim of confiscation.

Gardai would spend less time in court by increasing the type of evidence that could be given by certificate and the rules relating to guilty pleas would be placed on a statutory basis.

The Bill also removed the requirement for the nomination of district court judges to hear extradition applications, following the controversy last year over nominated Dublin District Court judges.

Mr O'Donoghue said the Bill was only part of a major programme of criminal law reform, but "it is nevertheless clear practical evidence of the Government's policy of zero tolerance towards crime - particularly, but not exclusively, drug trafficking".

He did not believe the answer to the community's drugs problem lay exclusively in criminal justice measures. But as Minister for Justice he had to introduce measures "which will disrupt to the greatest extent possible those who engage in the deadly trade of drug trafficking".

Mr Higgins derided the Minister's zero-tolerance policy and said that even before the election last year "he was forced to admit that this did not really mean zero tolerance". Instead it meant "whatever John O'Donoghue said it meant depending on whether there was a full moon and how Jackie Healy-Rae was feeling".

He described the Bill as the third plank of the Minister's crime package, this time on mandatory sentencing. "Only, when we read the Bill, we find that, true to form, mandatory sentencing does not really mean mandatory sentencing."

He cited the new offence of possessing a controlled drug with a value of £10,000 or more and a punishment of a minimum 10year sentence. "That would be a mandatory sentence were it not for the proviso that the court will not be obliged to impose 10 years if it is satisfied that there are exceptional and specific circumstances attaching to the offence or the offender." A guilty plea might also be taken into consideration.

The Fine Gael spokesman said the Minister had not presented a "shred of evidence" to show existing sentencing arrangements were unsatisfactory.

He also criticised the "arbitrary" way the offence of possessing drugs worth £10,000 would be implemented. All that would have to be proved is that a person had £10,000 worth of drugs. "This is a ridiculous way of computing the seriousness of the offence. The value of drugs can vary greatly from one part of the country to another," he said.

Ms McManus was concerned about the £10,000 offence and the abolition of the procedure for preliminary examination of indictable offences in the district court.

She said gardai regularly seized much larger quantities of cannabis than £10,000 and judges brought in much lower sentences. Cannabis should remain an illegal drug but it was not the same as heroin or cocaine.

The use of the "market value" criterion was unreliable and arbitrary and could be open to abuse. "Under this provision a garda or customs officer could in effect determine what sentence an accused person would get with all the attendant dangers of bias, inconsistency or even corruption."

Mr Upton said the Minister was attempting to rush the Bill through "as a populist response to crime and to send a message to the people that, however weakly, his slogan of zero tolerance still stands".

He thought the Bill was based on the belief that crime could be tackled exclusively through legislation.