SIPTU has accused the Health Service Executive and the Department of Health of ignoring their obligations under the Croke Park Agreement by reducing the working hours and take-home pay of home helps.
Last September, the HSE announced it was cutting around 600,000 home help hours - over 5% of the total - to save almost €11m.
However, SIPTU says that as a result, staff had witnessed a unilateral cut in hours and a savage reduction in pay, with some experiencing layoffs.
Arriving for a Labour Court hearing today, SIPTU Health Division Organiser Paul Bell said that in some cases, because of the way hours were being distributed, members cannot even sign on for social welfare.
He said it was not unusual to find a home help with a contract for 20 hours working for just two hours a week, resulting in a cut in pay.
He also stressed that service users were being affected by the reductions.
Mr Bell urged the Labour Court to insist that contracts of existing home helps are honoured in full, and that they be protected under the Croke Park Agreement.
He said that would mean their salaries would be protected, and they could be redeployed to where there is sufficient work.
He said the home help case would be a big test for the Croke Park guarantees, adding that somewhere along the line, home helps had been left out.
HSE Director of Human Resources Barry O'Brien said they were engaged in discussions with SIPTU within the Croke Park Agreement.
He said they were doing everything to maximise the number of hours for existing home helps, but there must be some acknowledgement that due to the very nature of the service there would be variables - including occasions where people may have reduced hours.
However, he said HSE evidence showed there were very many instances where there was a significant increase in hours.
Mr O'Brien said they needed more time to reach a comprehensive agreement on how to plan home help services going forward.