The union representing Border Force officers at airports around Australia, who have been banned from striking for at least three months by the industrial umpire, has vowed to keep fighting.
The Fair Work Commission has ruled in favour of the Immigration Department which appealed for the strike ban saying the public servants were endangering national security by walking off the job.
The 13,000 employees of the Immigration Department are among 120,000 federal public servants still involved in protracted disputes over pay and conditions.
The decision to suspend the actions for at least 90 days, comes after several days of intensive arguments in the Commission in Melbourne earlier this month between the Community and Public Sector Union and the Department of Immigration and Border Protection.
The department secured an interim order from the Commission after saying the actions posed an "unacceptable risk to the community".
The CPSU said at the time workers were fighting for the right to stage rolling 24-hour stop work actions in a manner that would not compromise safety.
The department told the Commission the strikes were seriously stretching the department's ability to staff its airport operations and was increasingly compromising the DIBP's ability to "assess and respond".
Immigration said it was battling to maintain its "surge deployments" the movement of public servants, mostly from Canberra, around the country to fill the gaps opened up by the strikes.
Fair Work commissioner Nick Wilson accepted the government's case finding the strikes could indeed hit immigration and border protection efforts.
"It becomes foreseeable that criminal or terrorist opportunistic behaviour become more likely as a result, since systemic weaknesses can be more easily identified and exploited," Mr Wilson wrote in his decision.
"The evidence shows this risk is not merely foreseeable, but that such behaviour more than likely occurred within the recent period of protected industrial action."
The union said it was disappointed, accused the department of playing games with its evidence and indicated that an appeal might be on the cards.
CPSU national secretary Nadine Flood said she rejected the notion that her union members would endanger national security.
"We're disappointed with this decision but not surprised by it, given the inherent seriousness of matters related to national security and counter terrorism," Ms Flood said.
"We absolutely reject any suggestion that the CPSU or our members in Border Force have done, or ever would do, anything other than act lawfully and responsibly to fight for their rights, conditions and take-home pay."
The union leader said she and her colleagues were not happy with the commission's decision or the allowances the department had been given in presenting its evidence.
"This decision has significant errors in key planks of the decision that this action constitutes a risk, including the extent of Border Force's surge deployment or strikebreaking capacity and whether slowing passengers and accepting delays during strike action is an inherent risk," she said.
"We will have more to say in coming days and are looking forward to being able to expose the serious issues raised by the conduct of the Department of Immigration and Border Protection and the Australian Border Force in this case."