GMB leader Paul Kenny, speaking at the TUC conference in London, told delegates he would go to prison if fighting against any further restrictions on trade union rights necessitated it.
Business Secretary Vince Cable has already warned that coalition ministers are minded to tighten existing laws if public sector unions pursue disruptive industrial action.
One plan recently floated by ministers is a statutory requirement for public sector employees to maintain a minimum level of service during strikes.
Some public sector workers such as police officers, firefighters and prison warders are already legally barred from striking.
Speaking at the first TUC annual conference in London since 1902, and the first at its headquarters since it was built in the mid-1950s, Mr Kenny called for a nationwide campaign of civil disobedience.
He said: “If going to prison is the price to pay for standing up to bad laws, then so be it. As long as I don’t have to share a cell with some expenses-fiddling MP, then I am willing to put my hat in the ring.
“The clock has stopped. Let’s make it clear – we will give them, any politician, the biggest campaign of civil disobedience that their tiny little minds can ever imagine.”
Unite general secretary Len McCluskey had set the tone ahead of the conference start by endorsing civil disobedience against cuts imposed by a Government which had not been directly endorsed by voters.
Workers would be within their rights to engage in a “campaign of resistance so that the government will take stock and perhaps take a step back from” its “attack” on public sector jobs and pensions. “I don’t think we can rule anything out”, he said.
“My view is that we should rule nothing in and nothing out. Every conceivable form of protest and action should be carefully considered, from civil disobedience through to co-ordinated industrial strikes.
“Everything should be considered in the face of the type of onslaught that we are looking at”, said Mr McCluskey.
