In Britain it was a moment of sober reflection, the 25th anniversary of the start of the miners' strike, the greatest defeat for the unions in modern times. Here in the US, by contrast, a long-overdue victory for organised labour may finally be at hand.

Last week the Employee Free Choice Act was introduced in Congress – in the Senate by none other than Ted Kennedy (below), in what might be a last roar of the ailing liberal lion. But what a roar it would be if the bill went through. You might think it is a matter of simple justice. But for employers, it signifies the advent of socialism or worse.

Listen to corporate America, and its allies in the Republican party and right-wing think-tanks, and you'd imagine the bill is a charter for union tyranny. It will increase organised labour's bargaining power, they complain. Of course it will; that is the whole point. Such objections might have merit if America were like pre-Thatcherite Britain, when the unions held government to ransom. But they don't. The US is one of the least unionised Western countries. Only 12 per cent of the workforce belong to unions, compared with 30 per cent during organised labour's golden age in the 1940s and 1950s.

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Employers point to the legislation's "card check" clause, whereby if a majority of workers at a company sign cards calling for the establishment of a union, and the process is ratified by the National Labor Relations Board, a union is automatically set up, with the right to negotiate a contract with management. If the two sides can't reach agreement, a government-appointed arbitrator will impose a contract. Opponents say the "card check" amounts to a public vote, which would permit intimidation, even violence, against workers who don't want a union. Whatever happened to the secret ballot, that foundation stone of American democracy, they ask, ignoring the Act's provision of a secret ballot, should a majority of employees request one.

Strip away the propaganda, though, and what's at stake is clear. The measure finally levels a playing field that has been tilted against organised labour ever since the Founding Fathers – or at least since a Philadelphia judge ruled in 1806 that an attempt by a group of shoemakers to secure a wage increase was an "illegal criminal conspiracy". Abraham Lincoln, who extolled the moral superiority of labour over capital, might have been a supporter of unions – but most often the movement struggled against the overwhelming power of the bosses.

The story of Jay Gould, financier, railroad magnate and archetypal "robber baron", sums up an era. In 1886, Gould was confronted by the so-called Great SouthWest Railroad Strike. Was he worried? someone asked. Not at all, Gould is said to have replied: "I can hire one half of the working class to kill the other half." Predictably, the strike failed.

More than a century later, employers still practise intimidation, albeit of a subtler variety. They can keep outside union organisers off the premises, and fire employees who agitate for unions, at the risk of derisory fines. Workers are told of the evils of unionised life. Jobs, they are told, will vanish as costs rise. If "socialism" comes to the shop floor, the entire company may be forced to relocate to friendlier, even foreign, climes. Honing these tactics are so-called union-avoidance consultants, "union-busters" as they are better known. They are masters of stalling, prevarication and generally exploiting every loophole in America's labour laws.

Yes, the employees may get a secret vote – but to what end? According to a recent study, out of 22,000 organising drives at companies between 1999 and 2005, only one in five succeeded in establishing a union that negotiated a collective contract with employers. And this despite polls showing that up to 50 million non-unionised workers would join if they could.

The country would benefit as well. In fact, the health of the unions and that of the national economy move almost as one. In the 1920s, unions were weak and corporate excesses contributed to the crash that followed. But in the Depression, membership soared, as the great social programmes of the New Deal helped build the middle class that took wing after the Second World War.

Just as in the 1920s, this latest "boom" has done little for the middle classes. A declining union movement was mirrored by a concentration of wealth among the rich. If labour reasserts itself, its extra bargaining muscle should help protect jobs and improve healthcare coverage, the two greatest worries of ordinary Americans.

And, you could argue, with stronger unions worldwide, this crisis might never have happened. In China, the other contributor to unsustainable global imbalance, a genuinely independent union movement might have forced that government to divert resources into consumption, rather than pile up a surplus that financed America's ruinous borrowing binge.

But will the bill gain approval? A couple of years ago, a similar bill foundered in the Senate. Back then, George Bush threatened to veto the measure. Now, President Barack Obama strongly supports it – as well he should, given the money and organisation the unions contributed to his victory. Several influential Democrats, doubtless prodded by their own corporate donors, are having second thoughts, however, claiming the priority is to put the economy to rights. But again, that is precisely the point. If organised labour had had a stronger voice, the US might never have got into this mess in the first place.