Trademark law is the body of law that protects a product or service mark, brand name, or logo from being used by other companies without their permission. In the United States, trademark laws are created and enforced through federal and state statutes and common law principles. The Supreme Court has also provided some guidance to the courts on how to apply trademark law.

The first requirement under common law for a mark to be protected is that it must be distinctive. This means that it must identify the goods of one company and distinguish those goods from similar goods produced by other companies. The most distinctive marks, which are called “arbitrary” or fanciful, are the most highly protected, such as Nike’s swoosh or Coca-Cola’s famous wave. Other types of trademarks that may be protected include “suggestive” marks, which hint or suggest the underlying product or service but do not describe it directly, such as Citibank’s blue globe for banking services or Jiffy Lube’s orange oil for car services. Finally, descriptive marks may be protected if they have acquired secondary meaning through use over time, such as Apple’s apple or Coke’s brown-colored soda water.

Another requirement of trademark law is that a mark must be used in commerce to qualify for protection. This has traditionally been interpreted to mean that the mark must be used in interstate or foreign commerce. Some defenders of trademark law have also relied on the Constitution’s treaty power to support their arguments, but this argument has been difficult for them to make because the Court has not yet been presented with a valid statute relying on it.

Trademark infringement is the most obvious type of trademark violation. When a company makes a mark that is too similar to an existing registered mark, it can be prevented from using that mark by filing a lawsuit seeking damages for trademark infringement. Depending on the type of infringement, the plaintiff can seek injunctions, or a judgment that a competitor has infringed on the trademark by using the mark.

In addition to infringement claims, trademark owners can bring a claim for trademark dilution. This type of claim is based on the theory that the continued use of a well-known mark will cause it to lose its distinctiveness and therefore be less effective in identifying a particular source of a good or service.

Trademarks can also be protected in other ways, such as through “trade dress” protection, which includes non-word identifiers like a color (such as Owens-Corning’s pink insulation) or the shape of a product’s package, for example (Coca-Cola’s unique bottle). However, the Supreme Court has held that such a use is not likely to confuse consumers and so is not an infringement of the trademark laws. Also, certain parodies of trademarks are protected under the First Amendment and thus cannot be subject to trademark infringement claims. This is a particularly important issue that the Supreme Court will soon decide.