This likelihood is typically determined using a multi-factor test that includes factors like the strength of the mark and evidence of any actual confusion.
A noteworthy hypothetical example of Initial interest confusion, first discussed in Brookfield v West Coast Entertainment,[1] involves two video stores.
However, with the appearance of the World Wide Web, Initial interest confusion claims have increased from 10 cases relying on the doctrine before 1990 to more than 100 between 1990 and 2005.
When Steinweg/Steinway left for America, the German business was sold to the three employees, Grotrian, Helfferich and Schulz, with permission to use the "Steinweg" name.
"[4] The Appellate Court, however, recognized the likelihood of confusion may not exist at the time of purchase, because those who buy expensive pianos can be considered to be well informed.
The motivation behind that decision was that "the Grotrian-Steinweg name would attract potential customers based on the reputation built up by Steinway in [the United States] for many years".
[2] Courts have upheld trademark infringement claims in domain names (cybersquatting), meta-tags that influence search engine results, and advertising keywords using the Initial interest confusion doctrine.
Brookfield developed a software, named MovieBuff, which consisted of a searchable database of past, current and upcoming films, their box office reviews, schedules, and other data.
West Coast, one of the nation's largest video rental store chains, subsequently launched on moviebuff.com an online movie database service similar to the one Brookfield had deployed.
The Court states "although there is no source confusion in the sense that consumers know they are patronizing West Coast rather than Brookfield, there is nevertheless initial interest confusion in the sense that, by using moviebuff.com or MovieBuff to divert people looking for MovieBuff to its web site, West Coast improperly benefits from the goodwill that Brookfield developed in its trademark."
[10] Judge Berzon of the Ninth Circuit, in a concurring opinion in Playboy Enterprises, Inc. v. Netscape Communications Corp., asked whether the court wanted "to continue to apply an insupportable rule", referring to Initial interest confusion as discussed in Brookfield.