Four weeks after the government moved to shut down Amish farmer Dan Allgyer for selling fresh, unpasteurized milk across state lines, angry moms who made up much of his customer base rallied on the Capitol’s grounds Monday to demand that Congress rein in the food police.

The moms milked a cow just across the street from the Senate and served up gallons of fresh milk, playfully daring one another to drink what, if sold across state lines, would be considered contraband product.

“The FDA really screwed up this time. They got between a mom and a farmer,” said Mark McAfee, who runs Organic Pastures Dairy Co. in Fresno, Calif., which under his state’s laws he legally sells at 400 markets, but which he cannot ship across state lines without running afoul of the Food and Drug Administration.

Raw milk has been making a comeback in recent years as consumers try to eat locally and fresh. But the FDA has been fighting back, arguing that there are big risks to drinking fresh milk and that it brings no benefits over the pasteurized version.

The most recent action to garner headlines came last month when the FDA went to court to stop Mr. Allgyer, the Amish farmer who runs Rainbow Acres Farm in Kinzer, Pa., from selling his raw milk to an eager customer base in the Washington region.

The FDA and the Justice Department sought a court injunction after FDA agents conducted a one-year sting operation, complete with fake aliases and lab testing, to determine that the milk they surreptitiously obtained from Mr. Allgyer was, in fact, unpasteurized.

Mr. Allgyer was not at Monday’s rally, but his defenders were infuriated that he had been targeted, and said it shows a government out of control.

“Despite the fact that there is no actual proof that anyone has ever been injured by milk from Dan’s cows, he is being treated as if he were a drug lord by our federal government,” said Jonathan Emord, a D.C.-based lawyer who says he has defeated the FDA in court more than any other lawyer. “He is being treated as if what he sells is contraband that will cause injury to anyone who gets near the substance. And this is fresh milk.”

The movement ties together the liberal and conservative ends of the political spectrum who are wary of government interference, and their thoughts were summed up in the sign that read: “Those who wrote the Constitution drank raw milk.”