Reforms will lead to 'rushed justice.
The Lord Chancellor, Lord Falconer of Thoroton QC, revealed new details of a programme of Legal Aid reform, which will dramatically shorten many long-running criminal trials.
But Liberal Democrat home affairs spokesman Mark Oaten said it was wrong to base trials on 'clock-watching'.
'It is right to ensure that victims, witnesses and defendants are not subjected to undue pressure, but rushed justice may not be fair justice,' he said.
'Legal cases should be conducted on the basis of thorough process not clock-watching.'
And in a sign that the reforms will face opposition from the legal profession, Bar Council chairman Guy Mansfield QC rejected a key plank of Lord Falconer's proposals.
Instead of securing virtually open-ended Legal Aid agreements, lawyers in criminal trials will be expected to submit bids to win contracts, said Lord Falconer.
If a case lasts longer than expected, the lawyers - rather than the taxpayer - will be obliged to pick up the costs.
But the Bar chairman commented: 'We reject price-based tendering for criminal defence work. It will create a Dutch auction for justice.
'It will decimate the young Bar and our already hard-pressed network of community-based high street solicitors.'
Lord Falconer said his proposals would also make trials quicker and more efficient by making prosecution and defence agree more areas of a case before going to court.
'The days of the 18-month trial are over,' he said, adding that most cases should not last longer than 'a few months at the very, very most'.
The changes - to be detailed in a strategy document - are designed to reduce the amount spent on criminal Legal Aid