Trademarks are vital to modern business. Modern trademark law in the U.S. is primarily traced to the Lanham Act passed in July 1946, but its foundation lies with the Commerce Clause of the Constitution (Article I, Section 8, Clause 3), which says "To regulate commerce with foreign nations, and among the several States, and with the Indian tribes."

The United States Constitution had been explicit about Patents and Copyrights as a vehicle to “promote the Progress of Science and useful Arts.” While trademarks did not necessarily meet that criteria explicitly, over time they came to be seen as an important part of commerce, and one that needed to be defined and protected in order to protect business owners and consumers. Prior to the passage of the Lanham Act, there were several attempts at laws and several notable legal cases that paved the way for the law’s passage.

• Taylor v. Carpenter: 23 F. Cas. 742 (C.C.D. Mass. 1844) (No. 13,784)
• Copyright Act of 1870: (July 8, 1870; 16 Stat. 198), also called the Patent Act of 1870 and the Trade Mark Act of 1870.
• Trade-mark cases (100 U.S. 82): 3 cases (United States v. Steffens, United States v. Wittemann, and United States v. Johnson) consolidated into a single appeal before the United States Supreme Court, which in 1879 ruled that the Copyright Clause of the Constitution gave Congress no power to protect or regulate trademarks.
• Trade Mark Act of 1881: (March 3, 1881; 21 Stat 502)
• Trademark Act: (February 20, 1905; 33 Stat. 724)

Prior to 1946, Congress held numerous trademark related hearings in 1912, 1914, 1916, 1919, 1925, 1927, 1930, and 1931, but it wasn't until January 1945 that H.R. 1654 was submitted to the House by Representative Fritz G. Lanham, a Democrat from Texas. The Lanham Act (Pub. L. 79–489, 60 Stat. 427, enacted July 5, 1946, codified at 15 U.S.C. § 1051 et seq. (15 U.S.C. ch. 22)) was intended to provide a federal system of trademark law and to:

provide for the registration and protection of trade-marks used in commerce, to carry out the provisions of certain international conventions, and for other purposes. ¹

H. Rept. 219 that accompanied the bill made clear that they wanted to centralize and clarify trademark law. The report included this:

There are many reasons why there would be a new trade-mark statute. The present act is substantially the act of February 20, 1905. It has been amended from time to time and supplemented by the act of March 19, 1920, which has also been amended in several particulars. The result is a confused situation.

There are many statutes dealing with trade-marks which are widely scattered and difficult of access. There are provisions dealing with trade-marks in tariff acts and other unlikely places. It seems desirable to collect these various statutes and have them in a single enactment.

Moreover, ideas concerning trade-mark protection have changed in the last 30 years and the statutes have not kept pace with the commercial development. In addition the United States has become a party to a number of international conventions dealing with trade-marks, commercial names, and the repression of unfair competition. These conventions have been ratified, but it is a question whether they are self-executing, and whether they do not need to be implemented by appropriate legislation.

Industrialists in this country have been seriously handicapped in securing protection in foreign countries due to our failure to carry out, by statute, our international obligations. There has been no serious attempt fully to secure to nationals of countries signatory to the conventions their trade-mark rights in this country and to protect them against the wrongs for which protection has been guaranteed by the conventions.²

It went on to make the case for the importance of trademarks:

The purpose underlying any trade-mark statute is twofold. One is to protect the public so it may be confident that, in purchasing a product bearing a particular trade-mark which it favorably knows, it will get the product which it asks for and wants to get. Secondly, where the owner of a trade-mark has spent energy, time, and money in presenting to the public the product, he is protected in his investment from its misappropriation by pirates and cheats. This is the well-established rule of law protecting both the public and the trade-mark owner. It is succinctly stated by Mr. Justice Frankfurter in Mishawaka Rubber and Woolen Company v. S.S. Kresge Company, decided on May 4, 1942:

The protection of trade-marks is the law's recognition of the psychological function of symbols.³

The new law was to take effect in July 1947, and any registrations made under the Act as it was originally passed, would last for 20 years. To keep up with the changes brought by a modernizing world, the law has been updated. For many companies, trademarks are even more important to their business strategy and identity than they were in 1946.