It's one of gastronomy's ultimate luxuries yet rarely far from controversy.

From July 1, the sale of foie gras – the butter-soft, forcibly fattened liver of duck or goose – is to be banned in California, the first state in the US to do so. It's a victory for animal rights protesters, who see pushing a feeding tube down the gullet of the bird to enlarge its liver by up to 10 times its normal size as cruel.

In the run-up to the ban – which, when broken, will carry a fine of $1000 –Californian restaurants have been busy serving the delicacy before it's too late. Thomas Keller, the only American chef to have two restaurants with three Michelin stars – French Laundry and Per Se – has been trying to have the ban overturned. Elsewhere there are rumours of civil disobedience and plans for circumventing the law, such as offering the foie gras free with a glass of wine.

In the UK (along with the Czech Republic, Denmark, Finland, Israel and Switzerland), production of foie gras is banned, though selling it is not, and many Scottish chefs say it's one of their most popular dishes.

They argue that sourcing only from French farms with the highest welfare standards justifies using the liver, which is unique in classic gastronomy. "If you know your foie gras is from birds that have been roaming freely in the fresh air, given lots of space and only force-fed during the last 12 days of their 18-week life, it makes a huge difference," says Derek Donaldson, the head chef of the Blythswood Square hotel in Glasgow. His foie gras and confit duck starter at and main of Buccleuch beef and foie gras burger at are the most popular items on his Classic menu. "As responsible chefs, of course we are mindful of the debate and understand the ethical argument, but foie gras is one of those unique products that is in demand and which is impossible to imitate."

Phil Lewis of Braehead Foods, which supplies Rougie French foie gras to more than 100 Scottish chefs, points out that force-feeding takes only one minute of a duck's entire life. He has spent time at the farms it is produced in, and says the birds are treated like kings because welfare is paramount. "If a liver is damaged through bruising caused by being reared too intensely, it is worthless," he said.

In any case, it seems there are the beginnings of a natural move away from foie gras in Scotland. Martin Wishart, The Herald Magazine's chef, explains: "Customers expect foie gras, but not all the time. What they do expect in my restaurants are top-end Scottish gastronomic items such as langoustines and hand-dived scallops.

"I don't have foie gras on the menu as much as before because it's not as important as it once was. We are constantly finding new ingredients. Monkfish liver is one example. It's similar in texture and colour, though not taste. It's like the foie gras of the sea. Their tiny livers are pinky-peachy in colour and to get them large enough to work with they have a very short season from January to March."

That's a sentiment fellow chef Tom Kitchin recognises. "I believe in foie gras and I eat foie gras, and I use it now and again on the menu," he says. "I was using it more but my cooking has changed and I feel it doesn't have a right to be on my Scottish/British menu. It's not an animal rights issue. But I do have an issue with people eating battery-reared chicken, and pork from pigs that have been hideously abused by farmers in the US. That's where I draw the line.

"Foie gras is the best luxury item. If you take that away, you kill gastronomy."

The Sustainable Restaurant Association, which has 1000 members UK-wide, acknowledges that foie gras is a live issue.

Managing director Mark Linehan says: "The SRA has been contacted by restaurants looking for more ethically reared foie gras.

"We would strongly encourage any restaurant currently serving foie gras, or intending to do so, to research carefully their supplier and the techniques they are using, in the same way we would with any meat, whether it be pigs, sheep, cows, chickens, ducks or geese.

"Cheaper supplies are available from Eastern Europe and the Far East and it is more difficult to monitor the farming methods in these countries." n