Final answer:
The legal foundation for federal trademark law in the United States is the Lanham Act, also known as the Trademark Act of 1946.
Step-by-step explanation:
The legal foundation for federal trademark law in the United States is the Lanham Act. The Lanham Act, also known as the Trademark Act of 1946, provides the primary source of federal trademark law in the United States. It establishes the requirements for trademark registration, the rights and remedies of trademark owners, and the penalties for trademark infringement.