Brookfield v. West Coast
United States Court clarified several times that as long as the use is done properly it is not a problem. But using in this case was not conducted for purpose of description or part of the common language. The use is conclusive mad for purpose of promoting a product that is not owned by the owners of the mark, by referral of surfers to competing site. This use it does not meet the criteria of fair commercial conduct.
Playboy Enterprises, Inc. v. Netscape
One of the first cases in which the keying issue was discussed in the United States was on the subject of Playboy Enterprises, Inc. v. Netscape Communications Corporation ruled on June 1999. On this issue the search engine allowed to display advertisements for porn sites every time a surfer looking for the words "playboy" and "playmate." Playboy Company objected and sued the search engine with respect to the dilution of its trademarks referenced unrelated competing signs trademarks.
In principle, Playboy petitioned the court to stop the use of trademarks in this specific context. Playboy chose a complex legal, since they were required to prove that there is "provides confusion" to prove its claim. The claim was denied by the District Court, and Playboy undermined.
The Court of Appeals turned the tables, and ruled that the search engine activity indeed misleading, and the search engine / browser Netscape earned from the confusion of the users who clicked on a search result that used the trademark of Playboy, and not those that refer to the website of Playboy.
On the Government Employees Insurance Company (GEICO) v. Google affair the trail prosecutors derived from enabling the plaintiff's registered mark keying and display advertisements for the company competitors.
The plaintiff relied on the provisions of Lanham Act, claiming that was a direct breach, indirect and contributory of the trade mark and also trade mark dilution and the creation of a false impression.