§§ 181-229b; P&S Act) regulates meatpacking, livestock dealers, market agencies, live poultry dealers, and swine contractors to prohibit unfair or deceptive practices, giving undue preferences, apportioning supply, manipulating prices, or creating a monopoly.

As the outbreak of World War I occurred and the cost of living rose, President Woodrow Wilson ordered the FTC to investigate the industry from the "hoof to the table" to determine whether or not there were any "manipulations, controls, trusts, combinations, or restraints out of harmony with the law or the public interest."

[1] The meat packing industry had also become a prime concern of Wilson's Attorney General Alexander Mitchell Palmer.

After threatening an antitrust suit, in February 1920 Palmer managed to force the "Big Five" packers (Armour, Cudahy, Morris, Swift and Wilson) to agree to a consent decree under the Sherman Antitrust Act (1890) which drove the packers out of all non-meat production, including stockyards, warehouses, wholesale and retail meat.

The Act also made stockyards quasi-public utilities and required yard officers, agents and employees to register with the government.

Stockyards were forbidden from dealing in the livestock they handled, and required them to maintain accurate weights and measures and pay shippers promptly.

[2] Chief Justice William Howard Taft reasoned the act was a valid exercise under the interstate Commerce Clause because it addressed the same problem as the injunction upheld in Swift & Co. v. United States (1905).

In 1996, a group of cattle feeders brought a class action lawsuit under the P&S Act against Iowa Beef Packers for captive supply agreements.

[2] The verdict was then thrown out by the United States Court of Appeals for the Eleventh Circuit in Pickett v. Tyson Fresh Meats Inc. (2005) because it found the meatpacker had a legitimate business reason to limit competition.

[2] The P&S Act is administered by the Grain Inspection, Packers and Stockyards Administration (GIPSA) of the United States Department of Agriculture.

The first major amendment to the Act was in 1958, when Congress expanded the jurisdiction of the United States Department of Agriculture (USDA) to include all auction markets operating in commerce.