The true figure for the number of criminal legal aid firms that will be forced out of business under Lord Carter's proposals is at least 800, independent research claimed this week - double what Lord Carter has predicted.

The research, commissioned by the Law Society and conducted by consultancy LECG, also revealed that profits under the proposed fixed-fee rates will be so low as to threaten the sustainability of the supplier base. Average profits for the most profitable group of firms - with 13 to 40 fee-earners - will be just 2%, while the smallest can expect a 6% loss.


At office level, the research predicted that at least 1,100 of the 2,700 solicitors' offices performing criminal legal aid work would have to merge to meet Lord Carter's minimum caseload of 200 matters. The report noted that if the remaining large offices were to expand their capacity by 20%, this would 'eliminate virtually all the small offices'.


The report said the proposed fees for lower-level criminal work were 'only fee neutral to a point'. It questioned whether the savings that are anticipated from lower travel costs and greater efficiencies can necessarily be relied on, noting that lower payment for travel is being introduced before the new boundaries come into force.


Law Society chief executive Desmond Hudson said the LECG study showed Lord Carter had 'got it wrong by 100%', and questioned whether other figures contained in the Carter review could be relied on.


Mr Hudson said: 'There is a very real risk that many more legal aid solicitors will not be able to afford to do criminal legal aid work. In 2010, don't be assaulted by your partner, don't have matrimonial problems, don't be assaulted by the police - because it will be very unlikely that you will find anyone out there to help you seek justice.'


Ian Kelcey, chairman of the Criminal Court Solicitors Association, said: 'This proves what we have been saying. The system is so fragile, to push ahead would put the whole criminal justice system in danger of collapse.'


Legal Aid Practitioners Group director Richard Miller added that the report showed the system could be 'significantly damaged' by the Carter proposals.


In response, Lord Carter said he was pleased that 'the overall move to marketisation is not being questioned'. He added: 'The Law Society worked with us over 12 months and had access to all the data we had available to us and our methodology. I think it would be hasty to rush to any conclusion having not yet had a proper opportunity to study the detail of the LECG work. I look forward to doing this.'


In a statement issued jointly with the Legal Services Commission, a spokesman for the Department for Constitutional Affairs said the 'serious and thorough' report would be fully scrutinised as part of the consultation process.


By Rachel Rothwell