Dan Brown, head of personnel strategy at Cosla, admitted that the legal opinion, obtained from Jim Peoples QC, contradicted Cosla's previous advice that detriment regulations be applied as a temporary protection to staff suffering pay cuts resulting from reorganisation.
'We would say that this latest opinion could suggest that some staff, not all staff, might have expected some permanent protection in terms of safeguarding their pay at the time of reorganisation,' Mr Brown said.
Staff who suffered pay cuts despite transferring to the same job at a new authority, for example, could have a good case at a industrial tribunal, Mr Peoples advised.
'Unison believes the only way forward is for the employers now to reinstate staff to their proper terms and conditions at the point of transfer on 1 April 1996,' head of local government Mark Irvine wrote to all Scottish Unison branches.
'If the employers are prepared to take this action, Unison will obviously be willing to discuss the matter through the Scottish negotiating machinery in the hope of achieving a settlement without reference to the courts.'
According to Cosla, there are more than 1,000 people in Scotland thought to be affected by the detriment regulations. However, this included those who applied for a job and were then given detriment and those who were doing a different job and receiving detriment payments.
'The opinion does not suggest that these staff should have been transferred on existing terms and conditions,' Mr Brown said.
Cosla is currently holding a series of meetings with member authorities in the hopes of coming to an agreed all- Scotland solution. The employers' side and staff side secretariats were also due to meet this week for informal talks.