Significant pay increases are to be sought by up to 10,000 lower-ranking civil servants on foot of an Equality Tribunal decision last month.
The tribunal found that seven female clerical officers in the Garda Síochána had been discriminated against because they received less pay than male gardaí who were doing "like work".
An appeal against the decision to the Labour Court is being considered by the Department of Justice, Equality and Law Reform.
However, the clerical officers' union, the CPSU, says the case provides the basis for further equal pay claims by 10,000 of its members in the Civil Service.
The union's general secretary, Blair Horan, said yesterday it would begin preparing the claims immediately and he was confident they would succeed.
Civilian clerical officers in the Garda are paid about €9,000 less per annum than gardaí doing the same work.
The tribunal rejected the department's argument that it had legitimate grounds, unrelated to gender, for paying the seven female CPSU members less than named male "comparators".
Mr Horan said two types of claim would now be prepared by the CPSU on foot of the tribunal's decision.
The first involved up to 1,000 employees of the Department of Justice who were being paid less than others doing identical clerical work, he said.
These included CPSU members employed in the Prison Service, who received significantly lower pay than prison officers on clerical duties.
A second type of claim would be made on behalf of the remainder of the CPSU's 10,000-odd members in the Civil Service, he said.
While these could not claim to be doing identical work with gardaí and prison officers on clerical duty, they were doing work of "equal value", Mr Horan claimed.
He added that there was provision for such a claim in equal pay legislation.
The CPSU, which has a predominantly female membership, has a track record in pursuing equal pay claims. In 2003 it reached a €34 million settlement with the Department of Finance on behalf of 5,000 civil servants. The claim arose from the fact that up to the late 1990s paper-keepers, most of whom were men, were paid about £50 a week more than clerical assistants, most of whom were women, for doing similar work. The union described the settlement at the time as the biggest equal pay claim conceded in Europe.
It is also pursuing a claim arising out of the benchmarking pay review of 2002. An Equality Tribunal decision against the union in that case has been appealed to the Labour Court.