President William McKinley, on May 25, 1900, signed into law legislation that has become known as the Lacey Act. Designed to combat interstate trafficking in illegally taken game, the Lacey Act became the first significant federal legislation to address the illegal taking and movement of fish and wildlife between and among the states and continues to be an oft-used enforcement tool today, but with wider application.

Under the general mandate of the Lacey Act as currently written, it is unlawful for any person to import, export, transport, sell, receive, acquire, or purchase in interstate or foreign commerce any fish, wildlife, or plant taken, possessed, transported, or sold in violation of any law, treaty, or regulation of the United States, any Indian tribal law, or any foreign law (16 U.S.C. § 3372). The sweep of the statute is broad because its enforcement can be based on any source of law that restricts the taking and possession of almost any type of wildlife that moves in interstate and foreign commerce.