Three of New Brunswick's public sector unions went to court Monday to seek improved rights and benefits for casual workers.

Tom Mann, executive director of the New Brunswick Union, told CBC News that under the province's labour laws, casual workers in the public sector cannot join a trade union until they work for six straight months.

Mann says that requirement prevents too many of them from ever getting the job security, pension plans and benefits enjoyed by regular employees.

"What happens in that six-month period is that many casuals come and go," Mann said.

"As a result of that, they're denied such benefits as access to the pension plan, to job security, to the accumulation of benefits such as vacation and sick leave and stat holidays."

"Many casuals come and go," Mann said. "They work a season, are let go, then they are brought back the following year.

"Our position is to make honest employees of them," he said. "If you need to reduce [the workforce], you lay them off with benefits under the provisions of the agreement."

Mann said unions have been pushing for better rights for 30 years, but the provincial government has done little to help.

"The Lord government ... has basically paid lip service," Mann said. "They say yes, the casuals are a vital part of the workforce, but we don't value them enough to give them access to association and equality under the law."

Premier Bernard Lord told CBC News the government has taken steps to address the rights of casual workers. 

Karen Mahoney knows all about being a casual worker from her stint as a casual employee at Miramichi's hospital from 1991 to 2003.

In documents filed with the N.B. Court of Queen's Bench, she says she worked without any job security or employee benefits. Every time she saw a new regular employee being trained, she feared she'd never have work again.

Danny Leger, the president of the Canadian Union of Public Employees in New Brunswick, said cases like Mahoney's are the very reason public sector unions are challenging the government in court.

"It's awful for the person in that position," Leger said. "If you don't know if you're going to be working next year or the next two years, how do you get a car loan? How do you get a mortgage?"

There are no statistics on the exact number of casual workers in the public sector, but thousands of provincial workers are affected by the rules.

Mann estimates the proportion of casual workers has jumped from 10 per cent of the total government workforce in 1980 to around 35 per cent.

The unions presented their arguments in court on Monday. There's no word on when a decision can be expected.