Reforms that will make it harder for key public sector workers to go on strike have been unveiled by the government.
Proposals in the Trades Union Bill would mean a strike in certain services - such as transport and schools - can only go ahead if 40% of union members support it and there is a turnout of over 50% at the ballot.
The bill would also impose a limit on the proportion of working time a public sector employee can spend carrying out duties on behalf of a trade union, while unlawful or intimidatory picketing would be treated as a criminal rather than civil offence.
Another key change is that union members will have to "opt in" to pay a political levy as part of their membership dues - a move that could seriously affect the Labour party's funding.
The head of the TUC, Frances O'Grady, said the moves were the start of "a slippery slope towards worse rights for all", while the head of train drivers' union Aslef, Mick Whelan, claimed the legislation "smacks of Germany in the 1930s".
Employment minister Nick Boles described them as "sensible and fair reforms" that would "balance the right to strike with the right of millions of people to go about their daily lives without last minute disruption".
A consultation on the proposals will now run until September.