Doesn’t federal law ensure that animals used in research and testing are treated humanely?
No law in the United States prohibits any experiment. The only federal law that applies to animals used for research—the Animal Welfare Act—is, for all intents and purposes, a husbandry statute that regulates the size of cages, cleanliness standards, provision of food and water, etc., for only a small fraction of the animals used in research. Animals in laboratories are routinely subjected to painful procedures and are usually killed afterward. Routine caging, isolation, handling, and even the laboratory environment itself are extremely stressful to animals.
