I recently traveled to a dairy farm in western New York to meet a farmer who had generously offered to show me his operation and let me try some of his milk.

After seeing his herd of 45 cows, we went inside a room connected to his milking barn, where he poured me a glass of milk straight from a stainless steel storage tank. It was cold, rich, and delicious.

it's now estimated somewhere between 1 and 3 percent of americans drink raw milk

It was also unpasteurized — that is, raw milk — which means it's entirely illegal to sell commercially across state lines in the US. It's also banned entirely in some states, like Maryland and Nevada.

A lot of people — from rural libertarians to urban foodies — want to change that. Over the past few years, enthusiasm for raw milk has grown among those looking for less-processed foods in our age of industrial agriculture: it's now estimated that somewhere between 1 percent and 3 percent of Americans drink raw milk.

"Since we were founded in 1998, the growth of raw milk has just been exponential," says Sally Fallon Morell, president of the Weston Price Foundation, an organization that promotes raw milk. She and other enthusiasts argue that it's more nutritious and more flavorful than pasteurized milk, and can be just as safe.

Food scientists strenuously disagree — and in terms of nutrition and safety, at least, they're pretty much right. Pasteurization doesn't affect the levels of most vitamins and nutrients found in milk, and on the whole, raw milk is much more likely to get people sick.

But is raw milk really dangerous enough that it should be illegal? It's a relevant question, given that 13 states have recently considered legislation that would ease raw-milk restrictions. Here's a look at the question from both sides.

A brief history of raw milk and the law

Pasteurization — the process of briefly heating a substance to high temperatures in order to kill bacteria — was first widely applied to milk in the US during the 1920s.

At the time, the country was rapidly urbanizing, so milk had to travel a greater distance before reaching most customers. In an era before widespread refrigeration and knowledge of proper sanitary practices, this gave bacteria inside milk more time to grow, leading to outbreaks of tuberculosis and other diseases.

In response, the FDA and other health officials began encouraging pasteurization. By the 1950s, the treatment was essentially universal for commercially sold milk. Since 1987, the FDA has banned all sales of unpasteurized milk for human consumption that has crossed state lines. Different states, though, have different rules regarding raw milk sold within their borders.

A number of states ban raw milk sales, or permit them only for animal use. But many others — including New York, where I drank raw milk — allow farmers to sell raw milk on the premises of their farms, if the farmers have a permit for raw milk sales and pass monthly inspections and tests for pathogens.

Still other states allow an arrangement called herd shares, in which customers can technically buy cows in a herd and pay a farmer to board them, thereby getting a regular subscription of raw milk delivered off-farm. And nine states allow raw milk sales in retail stores.

Even where raw milk sales are legal, though, they can be fraught. The farmer I met recently had a letter about his dairy sent out to a National Farmers Association distribution list, and it included praise of his raw milk production. But he sells most of his supply to a commercial distributor (which pasteurizes it), and the company was upset about the public attention called to his raw milk sales. As a result, he asked me not to name him in this article.

Raw milk is riskier than pasteurized milk

Proponents of raw milk often concede that pasteurization was a necessary innovation back in the early 20th century, when people didn't know about the importance of basic sanitary practices — like, for instance, thoroughly washing a cow's udders before milking them, to ensure that bacteria from their feces don't inadvertently enter the milk supply.

But raw-milk boosters argue that, nowadays, keeping a clean farm and rigorously adhering to such practices can cut down on the risk of an outbreak just as effectively as pasteurization. "The biggest criteria is having healthy animals that you're getting the milk from," the farmer I met told me as he showed me his herd. "At this dairy, the cows are raised on green grass, they've got fresh air, and they're very healthy."

public health officials insist that pasteurization remains essential

Apart from testing the milk for bacterial contamination, New York state also requires regular somatic cell count tests of the milk, which could indicate if a cow is sick. Like other raw milk enthusiasts, the farmer I met believes that these and other modern safeguards can eliminate the need for pasteurization. Many farmers also feel that grain-fed (rather than pastured) cows at conventional dairies are more likely to harbor dangerous bacteria — although there isn't strong scientific evidence for this claim.

Still, public health officials insist that pasteurization remains essential. "Good hygiene in a dairy environment can reduce the risk associated with raw milk, but it doesn't eliminate it," says Hannah Gould, who studies foodborne illnesses at the CDC. "Pasteurization is really the way to ensure that milk is safe to drink."

The outbreaks most commonly traced to raw milk, Gould says, are infections of Campylobacter, E. coli 0157, and Salmonella bacteria. They generally cause relatively short-term bouts of diarrhea and other gastrointestinal problems, but in rare cases, can lead to death.

A 2012 CDC report that tracked dairy-related disease outbreaks from between 1993 and 2006 backs up her assertion that pasteurization is key. Out of 121 outbreaks, 60 percent could be traced to raw milk or cheese, rather than pasteurized products.

Note that the graph above actually understates the difference in safety. That's because pasteurized milk is far more widely consumed than raw milk. It's tough to precisely calculate the relative risk of each — partly because there isn't great data on overall raw milk consumption — but the CDC study estimated that raw milk was 150 times more likely to lead to an outbreak. The report also concluded that states with softer restrictions on raw milk sales saw more frequent outbreaks.

Gould notes that raw milk is especially risky for children, the elderly, and people with weakened immune systems. Most recently, an outbreak of campylobacter transmitted via raw milk sickened 45 people in Utah, and was likely caused by one employee not properly cleaning a cow's udders before milking.

Raw milk is no more nutritious than pasteurized milk

When a customer stopped by the farm I visited to fill up a glass jar with a gallon of raw milk, I asked her why she made the extra effort to buy raw milk. "You can feel the life in it," she told me. "It's just so much better for you."

She wasn't alone in this: The notion that pasteurizing milk eliminates some of its nutritional benefits is one of the primary reasons why many people choose raw milk.

But, again, researchers disagree on this. "There's no evidence that pasteurizing milk makes it less nutritions," Gould says. Research shows that pasteurization barely affects levels of the main nutrients present in milk, like protein and calcium. It does slightly decrease the levels of some vitamins, such as B12 and C, but not to a huge degree:

Some raw milk proponents claim that the related process of homogenization — in which milk is pressurized and forced through small holes after pressurization — also reduces its nutritional value, by breaking up fat globules and altering the way they're absorbed into the body. Some hypothesize that this increases the long-term risk of heart disease. But research has not bore out this idea.

Finally, there's the claim that eliminating the "good" bacteria in milk has negative long-term effects — an idea related to the broader hygiene hypothesis, which argues that reduced exposure to bacteria in modern society has increased our risk of allergies and other autoimmune diseases.

Some studies have shown that kids who grow up on farms and drink more raw milk are less likely to develop asthma and allergies. Critics, however, say this can be explained by their greater overall exposure to all sorts of bacteria as part of the broader farm lifestyle — so a child growing up in an urban environment and drinking raw milk wouldn't see these benefits.

Taste, of course, is a more subjective matter. The raw milk I drank was indeed delicious — it tasted richer, sweeter, and more complex than normal milk. But that's much harder to quantify.

But does raw milk really deserve to be outlawed?

This is the big question. Raw milk might be more dangerous and no more nutritious than pasteurized milk But this issue isn't entirely black-and-white. For a few reasons, it's unfair to paint raw milk proponents as recklessly anti-science, like those who oppose vaccination.

For one, even though raw milk may be riskier than pasteurized milk, that doesn't necessarily mean it's the riskiest food out there. Milk is a relatively low-risk food to begin with, and some researchers estimate that the risk of getting sick from drinking raw milk is still lower than from eating home-cooked chicken or hamburgers.

The CDC provides detailed data on disease outbreaks caused by contaminated food going back to 1998, and during that time, raw milk or cheese have been involved in 149 different incidents (that doesn't mean it's the contaminated ingredient in each instance, just that it was suspected). It's tough to find a good comparison, because raw milk is an uncommonly-consumed food. But raw oysters, for instance, were involved in 144 incidents.

Of course, people are aware that raw oysters are a relatively risky food — partly because the FDA requires that all uncooked animal products need to be sold with a label saying so. So proponents argue that, by the same standard, raw milk could be legalized and labeled with the same warning.

Raw-milk boosters also point to the fact that in many other parts of the world, raw milk is sold freely, and has been for years. In Europe, it's used to make many traditional cheeses and nowadays is even sold in vending machines.

raw milk may be riskier, but it's not the riskiest food out there

Perhaps the most important factor is that drinking raw milk doesn't endanger others in quite the same way that not getting vaccinated does. Sure, you could get sick from contaminated raw milk and theoretically pass the bacteria along to others via what's called the fecal-oral route (through which bacteria from someone's feces somehow end up in someone else's mouth), and this does occasionally happen to people who didn't actually drink raw milk, but are in close contact with those that do. But on the whole, these pathogens are usually transmitted directly through contaminated food. Raw milk doesn't pose as much risk to others as, say, not getting vaccinated for measles does.

That means that the question of raw milk's legal status becomes a question not just about health, but about liberty — and the degree to which government should regulate it in the name of safety.

Fully legalizing raw milk would lead to more outbreaks of food borne diseases. It wouldn't increase nutrition. But there are plenty of other things the government could ban to make us as safe and healthy as possible — like, say, super-sized sodas, or alcohol — and by and large, we've rejected those bans, because most of us believe that we should be free to consume things for the simple reason that we like the way they taste.

For this reason, many libertarians have taken up raw milk as a cause célèbre: an obvious case, in their opinion, where government regulation has overreached. It's hard to disagree.

"It's a total double standard. The government allows cigarettes, and alcohol, but they don't allow raw milk," says Morell, president of the Weston Price Foundation. "It just seems crazy that they're in the business of telling us what milk to drink."

Update: This article was edited to include more information about cases where pathogens were passed on to people who did not drink raw milk.