Eleven trade unions have launched legal action against the government over plans to make it possible to replace striking workers with agency staff.
It emerged in June that then transport secretary Grant Shapps was preparing draft legislation introducing the controversial measure.
Ministers said it was necessary to prevent the public being disrupted by industrial action like the recent strikes which have brought the rail network to a halt.
In a major fightback, the TUC is co-ordinating legal action by the ASLEF, BFAWU, FDA, GMB, NEU, NUJ, POA, PCS, RMT, Unite and Usdaw trade unions.
They claim the government has broken the Employment Agencies Act 1973 by failing to consult unions, and is also violating “fundamental trade union rights” protected by Article 11 of the European Convention on Human Rights.
TUC general secretary Frances O’Grady said: “The right to strike is a fundamental British liberty. But the government is attacking it in broad daylight.
“Threatening this right tilts the balance of power too far towards employers. It means workers can’t stand up for decent services and safety at work – or defend their jobs and pay.
“Ministers failed to consult with unions, as the law requires. And restricting the freedom to strike is a breach of international law.
“That’s why unions are coming together to challenge this change in the courts.
“Workers need stronger legal protections and more power in the workplace to defend their living standards – not less.”
Richard Arthur, head of trade union law at Thompsons Solicitors LLP, which is representing the unions, said: “The right to strike is respected and protected by international law including the Conventions of the ILO, an agency of the United Nations, and the European Convention on Human Rights.
“The Conservative government should face up to its legal obligations under both domestic and international law, instead of forever trying to undermine the internationally recognised right to strike.”
A government spokesperson told Sky News in July: “The business secretary makes no apology for taking action so that essential services are run as effectively as possible, ensuring the British public don’t have to pay the price for disproportionate strike action.”