If you're reading this article with a cup of coffee, you should think twice before adding sugar to your brew. If it's from Cambodia, it may be tainted – not by chemical pesticides or fertiliser, but by human rights abuses. And if you're reading this in the European Union, here's something else you should know: EU trade policy is encouraging these abuses, and the European commission has yet to do anything about it.

Cambodia falls under the Everything But Arms (EBA) tier of the EU's Generalised Scheme of Preferences (GSP), which means that it – like other least-developed countries – can export sugar and a host of other products to the EU duty free. It might seem like a pretty sweet deal in theory, but it has not been so great in practice for many Cambodians. In fact, it's been a disaster.

The underlying issue is a fight over land. Cambodia is in the midst of a massive land-grabbing crisis that has seen nearly 2.2m hectares taken from mostly poor farmers and given to private firms as long-term economic land concessions. In just half of the country where the Cambodian League for the Promotion and Defence of Human Rights (Licadho) works, land-grabbing has affected at least 400,000 Cambodians since 2003. These victims are rarely, if ever, paid appropriate compensation.

Sugar is among the worst sectors for land-related human rights abuses, marked by violent evictions, the use of the military against civilians, and attacks and arrests of community activists.

In Koh Kong, for example, police destroyed villagers' crops and houses by bulldozer, attacking villagers who resisted. Similarly, in Kampong Speu province, 2,000 hectares of farmland belonging to more than 1,000 families were bulldozed under the protection of armed soldiers.

Meanwhile, on the sugar plantations themselves, there are several reports of widespread child labour. The EU bears some moral responsibility for this situation. Its preferential tariff treatment under the EBA has fuelled growth in Cambodia's sugar sector, and indeed allows it to flourish. A large proportion of sugar plantations in Cambodia were built explicitly for exporting sugar to the EU under the EBA.

The abuses linked to sugar are no secret. They have been thoroughly and vividly documented by human rights groups, both in Cambodia and abroad. The UN special rapporteur for human rights in Cambodia also concluded in a 129-page report published last September that "there are well-documented, serious and widespread human rights violations associated with land concessions that need to be addressed and remedied". Yet the European commission stands idly by.

It doesn't have to be this way. The EU's GSP regulations set up human rights safeguards, which require an investigation and potentially the withdrawal of trade preferences where serious and systematic human rights violations have been found. These same rules expressly allow for product-specific investigations, meaning a withdrawal of preferences for the sugar sector would not, for example, affect similar preferences afforded to Cambodia's important and lucrative garment sector.

The calls for an investigation into Cambodian economic land concessions and sugar began as far back as 2010 from Licadho and other NGOs. Members of the European parliament joined the chorus last October, and again earlier this year. But the commission has not implemented these legal safeguards.

On 15 May, the EU trade commissioner Karel de Gucht and foreign affairs representative Catherine Ashton flatly refused parliamentarians' most recent request, implying that they believed abuses in the Cambodian land sector were not "serious and systematic". They did not elaborate or explain how they came to a conclusion in direct opposition to that of the UN special rapporteur.

A statement from the EU embassy in Cambodia echoed the vagueness from Brussels, claiming that the land management situation in Cambodia "continues to evolve" and "elements of progress have been recorded". In other words, it seems the commission is going to ignore past abuses and just see what happens – because, you never know, it might get better.

That's not exactly the most proactive position. Nor is it the most coherent, given the Cambodian government's 20-year habit of baiting foreign donors with empty promises. It's also cold comfort for those who have been evicted from their land without compensation, as well as imprisoned activists, child labourers, and those who remain threatened by land-grabbing.

More to the point, though, the commission's refusal to investigate is very difficult to comprehend, considering the enormous power that the EU wields via the EBA: the power to foster and even create nascent industries; the power to boost undeveloped economies; and the power to do the right thing if a country doesn't respect international human rights norms.

The EU freely used the first two powers in Cambodia, much to its benefit. There's no dispute that it wields the third power as well. The only question left is whether it will use it.