There is no federal cruelty law—and technically, there cannot be. Animal cruelty is dealt with on the state level because the United States Constitution limits the areas in which Congress can pass federal laws applicable nationwide (Article 1, Section 8), and instructs that everything else is up to individual states to handle.
The U.S. Congress’s broadest Constitutional power is over activities that impact or affect international and interstate commerce. The term “interstate commerce” has been very broadly interpreted by Congress and courts throughout the history of our country—allowing Congress to legislate issues that don’t appear, on the surface, to be related to commerce “among the states,” like certain civil rights laws in the 1960s.
Acts of animal cruelty typically occur in a fixed place, and probably cannot be interpreted to impact interstate commerce—not yet, anyway—so the federal government has no jurisdiction over them. Some exceptions to the rule are federal laws involving the transportation of animals across state lines, such as the Animal Fighting Prohibition Enforcement Act.
“A person involved in the fighting of animals may be prosecuted under the Animal Fighting Prohibition Enforcement Act only when that person moved animals across state lines for the purpose of using them in a fight,” explains Carolyn Schnurr, Federal Legislative Manager, ASPCA Government Relations. “Most states’ animal fighting laws are adequate to prosecute activities that occur within the confines of the state. When an animal has been moved across state lines, however, the issue of prosecutorial jurisdiction becomes muddy. That is precisely why there is a federal law in place to deal with the issue of animal fighting. Either way—whether the activities were kept local, or involved interstate transport of animals—the offense will be covered under either state or federal law.”