Solicitors representing 1,449 Aer Lingus cabin crew have threatened to institute High Court proceedings against the Irish Congress of Trade Unions over its decision to split representation of the crew between IMPACT and SIPTU.
Congress took the decision following protracted discussions between the two unions.
A High Court action could have wide-ranging implications for the trade union movement.
Representatives of the cabin crew claim ICTU's decision goes against section 46 of its constitution, which stipulates that if 80 per cent of workers wish to transfer to another union the move should be approved.
Ms Nora O'Reilly, chairwoman of the IMPACT cabin crew committee, said up to 90 per cent of Aer Lingus cabin crew wished to transfer from SIPTU to IMPACT. She claimed well over 80 per cent had made their wish known when Congress took its decision in mid-October.
Congress was warned by solicitors acting on behalf of 1,449 cabin crew before it made the decision that it should not simply broker a deal between SIPTU and IMPACT. The letter said if it failed to adopt a proper interpretation of its constitution, workers would have no option but to institute proceedings.
Congress decided that only cabin crew who had submitted requests before September 29th, asking for their union dues to be paid to IMPACT instead of SIPTU, could transfer. It is claimed workers were not informed of this cut-off date.
An ICTU spokesman confirmed that Congress had received a letter last week from solicitors for the cabin crew. It had replied to the letter and had not received any correspondence since, he said.