The country's largest trade union, Siptu, has called for legislation to protect shop stewards from victimisation.
The union's biennial delegate conference in Tralee yesterday heard that union activists had been discriminated against and sacked for organising workers.
Paul Hansard of the Dublin construction branch said that if the union could not protect its shop stewards and guarantee that they would keep their jobs then it had no right to ask people to take up such positions.
Mr Hansard said that shop stewards working directly for construction companies were kept away from major jobs and isolated from workers on them.
"If you work for a sub-contractor and you are working on a job for a big company and you are a shop steward who brings issues on the site to the union, you will not work on that company's site again.
"Your company is notified and told to take that man off the site or you will not get any more contracts. If you work for an agency don't even think of becoming a shop steward because you will not work again," he added.
He cited the case of one shop steward who was sacked after organising workers and securing pensions and pay rates in line with registered agreements.
"All workers were called to a meeting at the company and ordered to leave the union immediately or they would face the same as him," he said.
Greg Price of the health professionals branch said that trade union activism came at a cost in the public sector as well as the private sector.
"We have been victims of bullying and discrimination. We have been undermined and told we can't represent particular issues or members," he said.
Mr Price said that activism often came at the price of being ignored or receiving no promotion. "It is important that we get more protection, whether it be enshrined in legislation or a code of practice drawn up between the union and the employers as part of social partnership," he said.
Delegates also called for legislation to copper-fasten the rights to trade union membership and recognition.
Legislation introduced in 2004 allowed unions to pursue claims on behalf of members in non-union companies through the Labour Relations Commission and the Labour Court. However, trade unions believe that this measure has been rendered null and void following a ruling by the Supreme Court this year in a challenge brought by Ryanair.
