When an allegation of trademark infringement arises, the case can be tried in federal court if the contested mark is registered, or in state court if not. In federal court, the registered owner is presumed to have the right of ownership and to exclude others from use of the mark.
In the absence of a federally registered trademark, state courts will examine factors such as how long each merchant has used the contested mark, how distinctive the mark is, whether the merchants maintained control of their marks, and whether they do business through similar channels of trade and in overlapping geographical regions.
State courts will particularly focus on public policy interests, and estimate the likelihood of confusion by the average consumer. For example, although a law firm database had for many years done business under the name "Lexis," an automaker was subsequently permitted to use the name "Lexus." The court reasoned that, as lawyers, Lexis customers are presumably sophisticated enough to avoid confusion, and that buyers of a luxury automobile are unlikely to be surprised when they do not receive a database report.