Enacted by Congress originally in 1946, The Lanham Act provides protection for trademarks via a federal registration system. The federal power to take this broad initiative is found by the Commerce Clause of the US Constitution. Co-existing with common law and state law trademark rights, the Lanham Act provides for protection of trademarks under federal law, protecting consumers against confusion in the marketplace, enforced primarily by the businesses who wish to assert a claim of trademark infringement or trademark dilution (if the mark is famous).
The Lanham Act is contained in Title 15 of the United States Code, sections 1051-1141.