Ten months ago the STUC launched Better than Zero, a campaign run by young workers in the fast food industry, hospitality and call centres. The leaders of the campaign, many of whom are not yet 20, are subject to minimum wage, zero hour contracts and a host of other bad employment practices.

Working in the largely non-unionised sector they neither expect nor receive union representation. They work alongside people, maybe a year or two older, who are better paid for undertaking exactly the same task. For these workers it is often the norm to receive a phone call an hour before they are due to start work to be told that they are not needed that day, or worse, to arrive at work only to be sent home.

Their response has been to get angry and to get organised. Over the past months, Better than Zero has championed a campaign of peaceful disobedience, disrupting the operations of major chains such a Sports Direct, organising flashmobs in the premises of the Stefan King owned G1 group, and, just a few months ago, forcing a reversal in the tipping policy of the Las Iguanas restaurant chain.

They are fighting for better legal protection but legislation is not enough. Most people do not go to the work in the morning thinking about their union, but the fact they are a member provides a degree of security.

If the Trade Union Bill becomes an act of parliament, the right to effective representation for public service workers will cease to be a negotiation between the employer and the employee, but regulated by dictats from Westminster. The right to take industrial action will no longer be subject to the normal rules of democracy but by ‘rules’ which no politician would dare to apply to themselves. Raising thresholds for industrial action ballots is one means by which the Tories seek to squeeze collective action. Even where a ballot is successful, the act gifts to employers a whole range of ways to break strikes.

Some laws are just bad, and some laws are just unworkable. The Trade Union Bill is both. With the support of the Scottish Government, councils and other enlightened employers, unions are determined to frustrate it. Councils across the country are already pledged not to comply with significant sections of the Bill. The Scottish Government, if not yet quite as explicit, has pledged to explore every avenue in order not to co-operate. They may well conclude that their duty to uphold human rights, sown into the fabric of the Scotland Act, or the devolution principle itself, brings them into direct conflict with the Westminster Government.

But, ultimately, if this Bill does come to pass, a moment will arrive that unions themselves will be forced to choose between the law and our fundamental duty to represent members, uphold the right to freedom of association and to withdraw labour.

What might this look like? Imagine a strike ballot where the Government’s arbitrary threshold is not reached, but where the union is entirely confident that a strike will be solid. Imagine a dispute in which the employer buses in agency workers to break the strike. Imagine a strike that is outlawed on a new minor technicality.

In these circumstances, it will not be the job of the STUC to dictate to unions how they should respond.

We are acutely aware that a driving purpose of anti-union legislation is to strip unions of precious assets in the case of legal breaches. Upholding principles can be a messy and expensive business.

But here is an STUC pledge: on the first occasion that a union decides to defy the law by ignoring illiberal picketing restrictions, or is faced with strike-busting agency workers, the STUC will call on every union to support the workers in dispute. We will mobilise all of our resources and all of our people in defence of the union or unions concerned. Our call for support will extend beyond the movement to all of those who believe in democracy and human rights. Picket lines, normally well managed peaceful and good natured, will become large scale manifestations of resistance. The young people from Better than Zero, shorn of rights and fighting an uphill battle for representation, will stand shoulder to shoulder with life-long trade unionists. We expect politicians, from across the Scottish political spectrum will stand with us too.

None of this we want. Industrial action is always a last resort. The over-riding priority of union reps is to represent their members, to make workplaces safer and more equal, to bargain collectively and to extend the principles of workplace solidarity into the public realm. Most enlightened employers recognise and support this. But if the anti-union Bill undermines these priorities, the Government should get ready for a major fight.