By Shanker Singham 

As the Agriculture Bill makes its way through Parliament, the UK faces a critical choice in its international trade policy. It is widely understood in trade circles that agriculture is the gate through which all trade policy flows. Long the bugbear of world trade, agricultural sectors all over the world have rigidly opposed any kind of trade liberalisation and managed to secure an exceptional status for the sector which is disproportionate to their economic weight. But the food we eat is so central to the way we think of ourselves as human beings that the agriculture sector has long maintained that it deserves special treatment.

The choice facing the Government is how to support farmers once we have fully left the EU and can carve out an independent trade policy. There has been a great deal of discussion about an amendment on banning imports of agricultural products that do not satisfy the UK's production standards. Labour has gone even further and suggested that American products in particular should be banned if they fail to live up to UK methods of production.

Such a measure has not been passed by any country in the world. Not even the most protectionist agricultural producer, the EU, has contemplated such a savage course of action. It would, at a stroke, turn the UK into one of the most restrictive trading nations in the world when it comes to agriculture.

It would also, importantly, violate a fundamental principle of WTO law, which requires food standards not to be used as a disguised form of protectionism, and that any attempt to ban products based on production methods should be even-handed and apply to all countries and the importer equally.

Labour's proposal would fail this basic even-handedness test because we already import food, both from the EU and elsewhere, which is produced by methods that fall below our own. Imposing different rules on the US would be a clear WTO violation. To make such a rule even-handed, we would have to rule out trade from most countries, including EU member states. That would render an EU-UK trade agreement impossible – though Labour claims to support such a deal.

Of course, the British people can decide whatever they want when it comes to trade or any other policy areas. But they ought to understand what the real-world consequences of this kind of protectionism would be, not least in terms of higher prices in the shops.

We can't have it both ways, many Conservative MPs extol the virtues of Global Britain in one breath, but then, without any trace of irony, espouse agricultural policies that would completely skewer any attempt to put such policies into practice. Indeed, they advocate policies that would make the UK a pariah state on the international trade stage, regarded by countries committed to the global trading system as even more extreme than the EU, about whom they have recently complained en masse.

For poorer countries these policies would drive a stake through the heart of their development. It is therefore particularly odd that they are being supported by a Labour Party for whom internationalism has long been an article of faith. It would be especially ludicrous for the UK to simultaneously maintain one of the highest foreign aid budgets in the world (of which it can be justly proud) and bar agricultural imports from the same countries it is ostensibly trying to lift out of poverty.