In recent months Kerry Kennedy, a scion of America's mighty Kennedy family, has been fuming about foie gras. This is not because of her concerns for animal welfare, though. What she is particularly worried about is human abuse. In particular, Kennedy alleges that the largest foie gras farm in America, Hudson Valley Foie Gras in upstate New York, is working its labourers obscenely hard. Each person has to feed the same 200-300 ducks once every four hours, seven days a week, for the 22 days it takes them to mature.

“There are people who have worked 10 years, with no break,” Kennedy says. “Not a single day off at all.” And what is most striking, Kennedy argues, is that this incessant labour is entirely legal, even today. New York state's 100,000-odd (mostly Latino) farm labourers are not covered by the normal legal framework that provides workers' rights, such as maximum hours or the ability to form unions.

Now, the managers of Hudson Valley Foie Gras deny that their workers are unhappy and have told local reporters that their staff want to work extremely hard. When I called the farm this week, a manager brusquely insisted that Kennedy was “misinformed”, but refused to answer any more questions about the issue. Whatever the truth, the absence of any social protections in a place such as New York state may come as a surprise for many FT readers, particularly those who are sitting in Europe today. And though people such as Kennedy - a daughter of Bobby Kennedy, and a human rights activist - are now campaigning to introduce a “farm worker fair labor practices act”, it will not be an easy fight. For the issue of farm labour cuts to the heart of much bigger ideological divides in America.