The case made by the supporters of the Transatlantic Trade and Investment Partnership (TTIP), the proposed controversial trade deal between the EU and the United States, rests on one very bold assertion and one very shaky assumption.

The bold assertion is that under TTIP the European economy will grow and that this growth will outweigh any economic negatives such as job losses and job displacement.

The shaky assumption is that, dazzled by the big numbers, ordinary citizens will care little for any further loss of democratic oversight of the way their economy is run and their services are delivered. They are prepared to believe, instead, that their governments, the big multinational institutions and big business can be trusted with the world's biggest trade deal.

This has tended to be the way of things in the past. But the response to TTIP has been different both because its proponents have been singularly unable to demonstrate its economic benefits and because, post the 2008 financial crisis, they have seriously underestimated the public mood.

The old trick of holding up a large number and hoping it will silence all criticism does not seem to work this time. In the context of the size of the European economy, euros130 billion of growth claimed is actually a very small number. Spread over a 12-year period it amounts to additional annual GDP growth of little more than 0.03 per cent, number so small that, by 2027, the task of measuring whether additional growth had been achieved as a result of TTIP would be statistically impossible.

At the same time, no serious impact analysis has been undertaken on the effect of TTIP on overall employment, and crucially, the impact of job dislocation, the process by which some areas and regions would lose employment, whilst others gained: derisory gains, enormous uncertainties.

Despite the rhetoric, TTIP has little to do with removing tariffs barriers and much to do with reducing protections to the environment and employment standards so that multinationals can trade with fewer inconvenient restrictions. The buzzwords are "standardisation" and "harmonisation". The truth is that corporate power is seeking to limit the intensely troublesome habit of some governments, some of the time supporting public ownership and protecting their citizens and the environment.

Against the general expectation that many standards would be harmonised through reduced protections, in one particular sector, the trend seems likely to be in the opposite direction. Under TTIP, the pharmaceutical giants will be lobbying intensively to make their patents longer, stronger and more far reaching, with the predictable negative impact on the cost of prescription drugs.

If the bold assertion of economic gain versus loss looks weak, weaker still is the assumption that citizens will stand idly by while the concentration of economic power continues apace at the expense of democratic accountability. Today sees the launch of the Scotland Against TTIP coalition, a coming together of a wide range of organisations, from trade unionists to local food campaigners and anti-poverty campaigners to environmental activists. This coalition is part of a growing movement across Europe that aims to prevent a massive corporate power grab taking place at the expense of democratic sovereignty. More than 1.5 million people in Europe have signed a petition calling for TTIP to be scrapped, and next Saturday a day of action will place with hundreds of events and demonstrations across the continent.

Until a leaked draft was obtained last August, the TTIP negotiations were being undertaken in secrecy. The Investor-State Dispute Settlement (ISDS), considered a cornerstone of TTIP by its strongest supporters, would allow international corporations to sue sovereign governments, bypassing existing legal procedures. This culture of secrecy and ignoring democratic process feeds directly into a narrative people increasingly suspect. Whether in Greece or Spain, where the traditional parties of government have been rejected and the diktats of international institutions challenged, or in the wider EU where opposition to the status quo is growing alongside a healthy disenchantment with the role of big finance, it is clear that traditional assumptions about the quiescent attitude of citizens and communities to the shaping of their economic futures cannot be relied upon.

This is one trade deal will not be passed on the nod.

Dave Moxham is deputy general secretary of the STUC.