There is, to this day, a ban on importing haggis into the US because it contains sheep lung, which is banned for import, as well as being banned for use in any food product for human consumption. ... The haggis produced in the US is not encased in a stomach, but in an artificial casing. read more
It appears that the Food & Drug Administration (FDA) banned lungs from human consumption in the US due to concern over how well the lungs could/would be cleaned during the butchering process. Fluids from the slaughtered animal can enter the lungs during processing. read more
No food for human consumption, whether made locally in the USA or imported from overseas, can contain sheep’s lung. Authentic haggis is a savoury pudding containing sheep’s pluck – the heart, liver and lungs – minced with onions, spices and oatmeal. read more