EDMONTON -- Alberta Premier Jason Kenney passed out earplugs in the legislature overnight as his government invoked a time limit on debate over a bill that strips some bargaining rights for 180,000 public-sector workers.

The bill passed Thursday morning following an all-night session during which Kenney walked up and down the aisles dispensing bright-orange earplugs to United Conservative caucus members so they could tune out criticism from the Opposition NDP.

New Democrat Thomas Dang said he was making a speech to the house when Kenney made his move.

"He had a big grin on his face. He was giggling. And he sort of (said something) like, 'Yeah, we don't have to listen to them anymore, especially this Thomas guy," said Dang.

"He sort of took it as a joke. And he thought that the whole process of this debate was a joke."

Dang said the plugs were given to more than 20 UCP caucus members and at least six of them, including government house leader Jason Nixon, put them in their ears. He couldn't say for sure whether Kenney used them.

Kenney was not made available for comment Thursday, but his office issued a brief statement:

"This was a harmless and light-hearted attempt to boost government caucus morale after being forced to listen to the NDP's insults, lies and over-the-top rhetoric for hours on end," said the statement.

Nixon echoed those remarks.

"It was a joke between members about the ridiculous speeches that were coming from the NDP," he said.

The bill was introduced less than a week ago and Kenney's government invoked time limits on all three stages of debate.

It delays contract provisions for reopened wage talks and binding arbitration for public-sector workers. Under current agreements, arbitration hearings must occur between now and the end of October.

Under the bill the hearings begin no earlier than November.

The bill imposes the delay on unionized workers who took pay freezes in the first years of their contracts but with the right in the final year to negotiate wages.

Workers affected include nurses, social workers, hospital support staff, prison guards, conservation officers, toxicologists, restaurant inspectors, therapists and sheriffs.

Kenney said Thursday the UCP didn't know about the wage reopeners until after the party won the April election. Once the government found out, it brought in the bill on the advice of Treasury Board and Finance, he said.

"The advice we received is that we needed to ... hit the pause button on this arbitration until we could come to the table in good faith with all of the necessary requisite information."

Kenney said he wants to hear first from a government-appointed panel examining Alberta's finances. That panel is to report by Aug. 15.

Political scientist Duane Bratt, asked to assess the earplugs imbroglio on a scale of light-hearted to democratic affront, said it falls somewhere in between.

"It was a juvenile stunt," said Bratt of Mount Royal University in Calgary.

He noted it was glaringly ironic in light of Kenney having made it known he wants to see more decorum in the house. Legislature members have already been banned from thumping on their desks to show their support of colleagues.

Unions have called the bill a drastic and illegal override of collective bargaining rights. They have promised to challenge the legislation in court but haven't ruled out job action.

Gil McGowan, president of the Alberta Federation of Labour, said unions are considering their next step.

"If the premier thinks he can tear up contracts and trample on workers' rights without a fight, he has another thing coming," McGowan wrote in a release.

"Earplugs aren't going to help him in weeks ahead because we can guarantee that if the UCP continues on this course, things are going to get really loud."