Trademark infringement

Trademark infringement is a violation of the exclusive rights attached to a trademark without the authorization of the trademark owner or any licensees (provided that such authorization was within the scope of the licence). Infringement may occur when one party, the "infringer", uses a trademark which is identical or confusingly similar to a trademark owned by another party, in relation to products or services which are identical or similar to the products or services which the registration covers. An owner of a trademark may commence civil legal proceedings against a party which infringes its registered trademark. In the United States, the Trademark Counterfeiting Act of 1984 criminalized the intentional trade in counterfeit goods and services.
If the respective marks and products or services are entirely dissimilar, trademark infringement may still be established if the registered mark is well known pursuant to the Paris Convention. In the United States, a cause of action for use of a mark for such dissimilar services is called trademark dilution.
In some jurisdictions a party other than the owner (e.g., a licensee) may be able to pursue trademark infringement proceedings against an infringer if the owner fails to do so.
Factors.
Courts consider various factors in order to determine whether a trademark was infringed.
This last factor, consumer confusion, is the main topic of debate in most cases.
Consumer confusion.
Where the respective marks or products or services are not identical, similarity will generally be assessed by reference to whether there is a likelihood of confusion that consumers will believe the products or services originated from the trademark owner.
Likelihood of confusion is not necessarily measured by actual consumer confusion if two products do not directly compete against each other but are in proximate markets. Then, to determine consumer confusion, a court may apply one of various factor tests. The primary test comes from Ninth Circuit Court of Appeals and is found in "AMF, Inc v. Sleekcraft Boats", 599 F.2d 341 (C.A.9) 1979. The Court there announced eight specific elements to measure likelihood of confusion:
Other Courts have fashioned their own tests for likelihood of confusion—like those announced in "In re E.I. du Pont de Nemours & Co"., 476 F.2d 1357, 177 USPQ 563 (CCPA 1973)"," known collectively as the "DuPont" factors.
Defenses.
The party accused of infringement may be able to defeat infringement proceedings if it can establish a valid "exception" (e.g., comparative advertising) or "defence" (e.g., laches) to infringement, or attack and cancel the underlying registration (e.g., for non-use) upon which the proceedings are based. Other defenses include genericness, functionality, abandonment, or fair use.
Globally.
The ACTA trade agreement, signed in May 2011 by the United States, Japan, Switzerland, and the EU, requires that its parties add criminal penalties, including incarceration and fines, for copyright and trademark infringement, and obligated the parties to actively police for infringement.
In many countries (but not in countries like the United States, which recognizes common law trademark rights), a trademark which is "not" registered cannot be "infringed" as such, and the trademark owner cannot bring infringement proceedings. Instead, the owner may be able to commence proceedings under the common law for passing off or misrepresentation, or under legislation which prohibits unfair business practices. In some jurisdictions, infringement of trade dress may also be actionable.