The DUP, UUP and Alliance Party voted against plans to reform trade union laws.
The Trade Union and Labour Relations (Amendment) Bill would have reduced the notice period before unions can take industrial action and lowered the minimum number of employees needed to take industrial action, among other measures.
Said Cllr Tierney: “It was extremely disheartening that MLAs, including many who would proudly categorise themselves as progressive and supporters of workers’ rights voted against supporting trade unions in the Assembly this week.
“The DUP, UUP and the Alliance Party rejected proposals to make it easier for workers to go on strike when they feel they are being treated unjustly.
“I have yet to hear an adequate reason from any of these parties why they feel our workers do not deserve to have as many protections as possible in place.
“All parties recently gave commitments to the trade union movement that we would work together to enhance workers’ rights. This feels like a betrayal.
“We still have some way to go when it comes to workers’ rights in the North.
“Too many people are in full-time employment, yet still struggling to get by.
“Many are forced to rely on zero hours contracts which means they do not know when they are working from one week to the next.
“And every year we learn that businesses are still indulging in practices like paying below the minimum wage and not abiding by employment law.
“In recent weeks we have seen numerous examples of staff being forced to go on strike to stand up for themselves and get the treatment they believe they deserve.
“This week the Assembly had the chance to stand up for workers and it’s regrettable that the DUP, UUP and Alliance Party stopped that from happening.”