Two major Nova Scotia unions say they are mounting fresh challenges against the province related to their contract disputes, announcing their intentions Wednesday in the midst of a provincial election campaign.

The Nova Scotia Teachers Union said it will launch a charter challenge in Nova Scotia Supreme Court against Bill 75, the legislation the Stephen McNeil-led Liberal government used to impose a contract on teachers in late February.

A press release issued by the union on Wednesday said the government's actions "violated NSTU public school members' rights to freedom of association and freedom of expression guaranteed under the charter."

Bill 75 was implemented after teachers rejected three tentative agreements between the union and government.

"The government actions were both reckless and inappropriate and prevented teachers from negotiating a fair contract that included needed reforms to improve classroom conditions," NSTU president Liette Doucet said in the release.

Bill 75 followed a contentious dispute between teachers and the province that saw teachers begin a work-to-rule campaign, meaning teachers only did what was required of them in their contract. Teachers also staged a one-day strike, the first in the union's 122-year history.

McNeil responds

McNeil, who hopes to lead his Liberals to victory in the May 30 vote, said Bill 75 doesn't violate the Charter of Rights and Freedoms.

He said his government negotiated three different tentative contracts with the NSTU and the offers were rejected by the union's membership, despite the fact that "each time we continued to put more on the table."

McNeil said the government had no choice but to implement Bill 75.

"What was happening was it was creating a greater impact on the classroom, there was a greater impact on students. It came to the point where this had to stop," the Liberal leader said.

Should the charter challenge proceed, McNeil said his government would defend its position.

"We're very confident that our position will stand the test of time. We'll wait to see."

NSGEU filing for arbitration

In a separate move, the union that represents 7,300 civil servants who work for the province is filing for arbitration, saying negotiations with the Nova Scotia government over a new contract are at an impasse.

Jason MacLean, president of the Nova Scotia Government & General Employees Union, said in a news release Wednesday that "bargaining was moving backwards" during two negotiations with the province in April that had a conciliation officer present.

McNeil has said if a union representing provincial employees calls for arbitration he would proclaim Bill 148, which would impose a wage package on those workers.

When asked Wednesday about the NSGEU decision to seek arbitration, McNeil said "that's an option they can do and we'll look at our options."

McNeil said "we'll look at our options" but added he didn't feel pressured to proclaim Bill 148.

"We're a long ways away from getting an arbitrator," he said.

The teachers union had not yet announced its court challenge when McNeil spoke with reporters.

'Not worth the paper it's written on'

The NSGEU represents a wide range of civil servants, from administrative professionals to correctional officers to architects.

MacLean has said he's not worried about Bill 148 because he believes the bill would not withstand a court challenge.

"We believe Bill 148 is not worth the paper it's written on. The premier is more than welcome to try and proclaim that on us, because that's a waste of taxpayer money," said MacLean told CBC News on Wednesday.

Contract offer

On Tuesday, NSGEU members voted 97 per cent in favour of arbitration if an impasse was declared, a union news release said.

Arbitration is a dispute resolution process in which an independent arbitrator or arbitration board renders a decision, binding for both the employer and union.

The government's offer is a four-year contract with no increases in the first two years, followed by a three per cent increase in the final two years. The offer would also remove the public service award, a deferred wage benefit negotiated in the 1980s that is paid out upon retirement.

The real issue is not wages, MacLean stressed — it's the removal of the public service award.

"What we're looking to do is maintain what we have in our collective agreement as of 2015," said MacLean.

Union members rejected the province's year-old contract offer in December.