Among a series of new pieces of legislation, California will be voting on Proposition 37 - a statute that will require foods containing genetically modified organisms to be labelled.

The basis of Proposition 37 is that raw or processed food offered for sale to consumers if made from plants or animals with genetic material changed in specified ways must be labelled.

The Proposition prohibits labelling or advertising such food, or other processed food, as "natural" and exempts foods that are: certified organic; unintentionally produced with genetically engineered material; made from animals fed or injected with genetically engineered material but not genetically engineered themselves; processed with or containing only small amounts of genetically engineered ingredients; administered for treatment of medical conditions; sold for immediate consumption such as in a restaurant; or alcoholic beverages.

The new piece of potential legislation has drawn vociferous, heartfelt and sometimes vicious lobbying by both those for and against.

The Yes to 37 campaign group maintains: "Prop 37 gives us the right to know if our food has been genetically engineered. It helps us make the right food choices for our families by putting a simple label on the groceries we buy and telling us if our food has been genetically engineered.

"Simple and clear labels. No cost to consumers. No loopholes - that's why a broad and diverse coalition from the Sierra Club, to farmers, nurses, doctors and the Consumer Federation of America say YES to 37.

"Opponents are spending nearly a million dollars per day trying to make it complicated. But really it's simple - we have the right to know what's in our food."

However, the No to 37 campaign group maintains: "Proposition 37 would ban the sale of tens of thousands of perfectly-safe, common grocery products only in California unless they are specially repackaged, relabelled or made with higher cost ingredients.

"Prop 37 is a deceptive, deeply flawed food labelling scheme that would add more government bureaucracy and taxpayer costs, create new frivolous lawsuits, and increase food costs by billions - without providing any health or safety benefits.

"Thousands of common foods are made with ingredients from biotech crops. Prop 37 bans these perfectly safe foods only in California unless they're specially relabelled or remade with higher cost ingredients.

"Prop. 37 is full of absurd, politically motivated exemptions that make no sense. It requires special labels on soy milk, but exempts cow's milk."

As the time to vote on the law draws closer, the gap between the two sides appears to be narrowing.

In August, a poll of voters in California had the Yes lobby leading by three to one. A more recent poll by the California Business Roundtable and Pepperdine University has seen support from Proposition 37 drop by 19 per cent.

According to some commentators, the effect of Proposition 37 will not be seen so much in the letter of the law - what should and should not be labelled - but in the way US citizens feel about GM foods in general.

According to Michael Pollan in the New York Times: "One of the more interesting things we will learn on Nov. 6 is whether or not there is a "food movement" in America worthy of the name - that is, an organized force in our politics capable of demanding change in the food system.

"What is at stake this time around is not just the fate of genetically modified crops but the public's confidence in the industrial food chain. That system is being challenged on a great many fronts - indeed, seemingly everywhere but in Washington."

Tom Philpott in Mother Jones said: "Unlike the European Union, the US government doesn't require food manufacturers to disclose their use of genetically modified organisms.

"Californians appear ready to change that. And if they do approve the measure, food companies might well start disclosing GMOs nationwide, since it would be expensive and cumbersome to produce one set of labels for California, home to 12 per cent of the nation's population, and another for the remaining 49 states."

Certainly, California has a track record in blazing the trail for provocative food and farming legislation.

In 2008, Proposition 2 caused a stir when it was passed in California, laying down the legislation in the state to ban battery cages for laying hens and impose the introduction of enriched cages.

The Standards for Confining Farm Animals (2008) created a new state statute that prohibits the confinement of farm animals in a manner that does not allow them to turn around freely, lie down, stand up, and fully extend their limbs. The law that includes farrowing sows, calves and laying hens is set to go into full effect on 1 January 2015.

Voters in other states had previously voted to eliminate calf and pig crates, but Proposition 2 in California in 2008 was the first time voters were asked to eliminate the practice of confining chickens in battery cages. It was passed by 8,203,769 votes to 4,731738 - 63.5 per cent to 36.5 per cent.

Passing the statute in California then led to other states following suit, in particular Idaho, Nevada and Michigan.

However, with different laws appearing in different states there was a variety of interpretation about what was required for the welfare of the hens leading to confusion and even court cases to have the laws interpreted.

Earlier this year the Humane Society of the US and the United Egg Producers, on the surface two unhappy bedfellows, came together to have a federal law on the welfare of laying hens introduced.

The legislation H.R. 3798, the Egg Products Inspection Act Amendments of 2012, will:

• require conventional cages to be replaced during an ample phase-in period with new, enriched colony housing systems that provide all egg-laying hens nearly double the amount of current space;
• require that, after a phase-in period, all egg-laying hens be provided with environmental enrichments, such as perches, nesting boxes and scratching areas, that will allow hens to express natural behaviours;
• require labelling on all egg cartons nationwide to inform consumers of the method used to produce the eggs-"eggs from caged hens," "eggs from hens in enriched cages," "eggs from cage-free hens" and "eggs from free-range hens";
• prohibit feed- or water-withdrawal moulting to extend the laying cycle, a practice already prohibited by the United Egg Producers Certified programme;
• require standards approved by the American Veterinary Medical Association for euthanasia of egg-laying hens;
• prohibit excessive ammonia levels in henhouses; and
• prohibit the transport and sale of eggs and egg products nationwide that do not meet these requirements.

The regulations will take between 15 and 18 years to be phased in and enforced but will lay down a minimum of 124 square inches of space for white hens and 144 for brown hens nationwide. At present, the majority of hens are each provided 67 square inches of space, with up to 50 million receiving around 48 square inches.

The changes in the law have been met with stiff and vocal opposition, mainly from organisations outside of the poultry sector - cattlemen and pig producers.

As 5M Publishing's senior editor Chris Wright reported from World Pork Expo in June this year, the National Pork Producers' Council feared that if it becomes law it will have deeper repercussions for the rest of the agricultural sector.

Audrey Adamson, NPPC Vice President of Domestic Public Policy said that if this law passes, this would be the first time the US government sets "x by y" size standards for raising animals and she added that the legislation has nothing to do with food safety standards.

The NPPC is also worried about what the Egg Bill will do to supply, prices and production costs of eggs.

The pig sector says that producers should not be forced by government to produce with a certain system and the pig producers are at present seeing changes with the abolition of sow crates driven by public opinion and leading processors, retailers and foodservice groups.

These fears that have followed in the wake of passing of Proposition 2 over the last four years now overshadow the similar legislation that is being put forward in California on presidential election day.

California might be leading the way with Proposition 37, but it could also be introducing piecemeal legislation in coming years in other states.

Proposition 37 could also see a bitter backlash from the industry or it could also be the forerunner of federal legislation if it receives public approval.

What is certain is that more questions are likely to be raised over the efficacy and validity of labelling genetically modified organisms following the vote - whichever way it goes.