Centrelink will front the industrial tribunal on Friday morning, trying to stop its public servants from embarking on a six-day campaign of micro-strikes between February 15 and February 24.
The Fair Work Commission will hear an application in Canberra on Friday from the giant Department of Human Services to rule planned industrial action by workers at Centrelink, Medicare and Child Support illegal.
The Community and Public Sector Union says it will "staunchly" oppose the action by DHS, alleging it is based on false allegations.
It is understood the department will argue the planned strike is at least in part a protest against the policies that have led to the ongoing "robo-debt" debacle, which would make the action illegal under the Fair Work Act.
But the department says the union has made public statements clearly linking the strike with the ongoing debt recovery controversy, which has seen considerable internal criticism aimed at the welfare agency, and public servants have no legal right top strike against departmental policy.
But the union says its strike is squarely aimed at forcing a settlement to the bitter dispute over conditions and pay that has raged between DHS and its 34,000 workers for three years.
CPSU National Secretary Nadine Flood issued a statement on Thursday, saying the department's legal action against the strike was "ridiculous".
"This is an extraordinary attempt by DHS to stop our members from striking or letting their customers know what's happening," the union leader said.
"It's patently ridiculous for the department to claim strike action is just about robo-debt when our members have been taking similar industrial action for 18 months over the Government's attack on their rights.
"Enterprise bargaining in this agency is a mess and we'll be strenuously defending the right of our members to strike and take other action like handing statements to their clients to protect their workplace rights.
"Senior management in the department has a terrible track record of trying to hide problems instead of fixing them, and this continues that pattern."
A departmental spokeswoman said the planned industrial actions was illegal.
"The basis of our complaint is that the union's reasons for the industrial action are unlawful as they do not comply with the Fair Work Act 2009," she said.
"The Act specifies that protected industrial action must relate to enterprise bargaining.
"The CPSU has publicly cited reasons for the industrial action which are unrelated to the current enterprise bargaining process."
