A strike is a form of industrial action. Although each employee will be in breach of their contract of employment, the union and its officials calling the strike will be protected against legal action, provided the strike (or other form of industrial action) has been called in accordance with the law.

This legislation sets out many detailed requirements including that:

• the action is in relation to a work dispute (this would rule out, for example, action for political reasons);
• the dispute must be with your own employer (this makes it difficult to plan industrial action in industries where groups of workers, although working alongside each other, have different employers, for example as a result of outsourcing or the use of facilities management companies to provide some services);
• a secret postal ballot has been held, following detailed rules, including rules as to exactly what words must appear on the ballot paper;
• there is a majority in favour of the action;
• the ballot has been independently scrutinised (if more than 50 people are involved); and
• notice has been given of the industrial action.

The UK has some of the most complex and restrictive industrial action laws in the developed world. Even so, the government has decided to make it even harder to strike by introducing a host of new changes, including higher turnout and ballot thresholds, changes to the rules on what must be written on the ballot paper and to the amount of notice that must be given to the employer, limits to the life of the strike ballot and the introduction of a new requirement for a 'picket supervisor'.

These new rules are contained in a new piece of legislation – the Trade Union Act 2016, which came into force in March 2017. You can follow news about the implementation of the Trade Union Act, and guidance on striking without falling foul of the new laws, on the TUC’s main website.

In a formal complaint to the International Labour Organisation Committee of Experts, the TUC has condemned the Trade Union Act as a "full frontal assault on the industrial and political freedoms of the British trade union movement".