In 1984, Vogue magazine published "A Raw-Milk Warning: A New and Dangerous Fad," an article reporting that drinking unpasteurized milk greatly increased the risk of salmonella infection. Along with similar government warnings, the story prompted a number of consumer lawsuits, and in 1987 the Food and Drug Administration banned the sale of raw milk for human consumption across state lines.

Two decades later, with roughly half of states allowing the sale of raw milk, the debate over the product, its dangers, and its merits has been re-energized. In Pennsylvania this month, sales of raw milk were banned at dairies that tested positive for Listeria monocytogenes. In Maryland, lawmakers recently rejected a bill that would have allowed the sale of raw milk in stores. And in California, dairies have sued to overturn a new law that sharply restricts the amount of bacteria that can be present in raw milk. While public-health officials say the law protects consumers, raw dairies say it will drive them out of business.

Culture war. Behind these maneuvers is a modern-day culture war. On one side are the proponents of raw milk, who claim that it tastes better and confers certain health benefits, including as a treatment for acne and asthma, because of microorganisms otherwise killed off by pasteurization. Mark McAfee, a co-owner of Organic Pastures in California, says he will sell about 5 million gallons of the stuff this year and that business is growing by about a million gallons annually.

Countering McAfee and his supporters are public-health officials, citing decades of research, who say that raw milk has been linked to hundreds of cases of food-borne illnesses and that little hard evidence exists to support the claim of salubrious properties.

On the first point, the data are compelling. In 2001 and 2002 more than 500 people fell sick from raw milk products, according to the Centers for Disease Control and Prevention. From 1972 to 2000, the CDC documented 58 outbreaks from raw milk, or roughly two per year. In many cases the culprits were virulent strains of salmonella, listeria, or Campylobacter. (Pasteurized milk is not problem free, either: Contamination can occasionally occur after pasteurization and cause outbreaks, such as one that sickened thousands of people in 1985.)

The debate ultimately is a tug of war between individual rights and government regulation, and in California, it has taken a passionate turn. According to the law, which took effect January 1, packaged raw-milk products cannot have more than 10 coliform bacteria per milliliter. High numbers of coliforms can indicate a dirty milking environment and, officials argue, a heightened risk of bacterial contamination. In February, officials cited excess coliform counts at Organic Pastures and another farm and temporarily banned their sales of raw cheese.

Health experts say that the tough coliform limit is consistent with federal standards for pasteurized milk. But advocates note that coliform measures can fluctuate wildly and were first developed to make sure that the pasteurization process was properly working. "Coliforms," says Gary Cox of the Farm-to-Consumer Legal Defense Fund, "is not an indicator of safety" but of sterility. A court granted the farms' request for a temporary restraining order, and a hearing is set for April 25.