The ASTI teachers' union has lodged a High Court challenge against the Government for financial penalties that were applied to its members because of industrial action they took two years ago.

The union has lodged papers with the court alleging unequal treatment because of the Government’s decision not to subject nurses who took industrial action earlier this year to the same penalties.

The union alleges that the decision to punish its members but not nurses was "irrational, arbitrary and disproportionate".

It alleges that the Government’s action breaches common law principals of equal treatment and transparency, and goes against natural and constitutional justice.

ASTI members had increments frozen and other payments due to them delayed under so-called FEMPI legislative measures designed to punish unions deemed to have stepped outside of collective bargaining agreements as a result of industrial action.

While all ASTI members suffered financially to some degree, the penalties were most severe for new entrants to the profession.

Many younger teachers continue to suffer because annual salary increments due to them continue to lag behind. The union estimates that a significant number of teachers are still losing between €1,000-€2,000 annually as a result.

The Department of Education has estimated the total financial loss to teachers as a result of the FEMPI penalties at €15m.

The union says summons’ were issued in the High Court yesterday and are expected to be served on the Government today.

The union is looking for a declaration from the court that the Government did not have the right under legislation to treat ASTI members unequally from members of the INMO nurses union, or if they did, that the legislation in question is incompatible with the European Convention on Human Rights.

General Secretary Kieran Christie says the union is demanding full restoration of all FEMPI related losses that its members suffered.

He told RTÉ News that the fact that the nurses were not subjected to the same penalties has made it clear that the punishment meted out to ASTI teachers was at the discretion of the Government.

Mr Christie said this unfair treatment was "a bitter pill to swallow" for his members.

Last week Minister for Education Joe McHugh said his department would engage with the union on the issue.