In many jurisdictions this test has been superseded by the concepts of similarity and likelihood of confusion, due to the harmonizing effects of the Agreement on Trade- Related Aspects of Intellectual Property Rights.
Where mark X is not identical to a registered trademark, the use of mark X may still amount to an infringement if it is “confusingly similar” to the registered trademark. Mark X may share elements of spelling or style that would lead a reasonable observer to believe the trademarks were related.
For example, in the computer industry, Microsoft has become such a well known trade name and trade mark that other businesses in the industry may want to use the term “micro” or “soft” in their names.
As Microsoft generally does not hold exclusive rights in these terms, it would need to establish that any trade names or trademarks which include these terms are confusingly similar to “Microsoft”.
The reputation attaching to a trademark is also significant, such that “Microsoft” or “Micro Software”, although clearly not identical, could potentially be confusingly similar and amount to an infringement.
In addition, the style of a trade mark, such as a logo or font, can become relevant. For example, Microsoft products are distinguished in the marketplace by a consistent font.
Competitors may not use the same font on their product, particularly when using a name which would not be confusingly similar except for the use of the font. For example, a brand called “Microsystems” would most likely not be confused with Microsoft.
However if Microsystems used the same font as Microsoft, it would be confusingly similar. Some styles, like the script used on Coca-Cola(TM) products, are so well known that even a completely different name in a similar script could be held to be confusingly similar.
However, courts can also take judicial notice that an infringing mark is confusingly similar if it is obvious to even a casual observer.
In an action for Infringement, the basic inquiry generally involves a same set of questions. They are:-
(i) How strong is the mark being defended?
(ii) How similar are the products in question
(iii) How similar are the marks in question
(iv) Have consumers actually been confused
(v) Which marketing channels have been used?
(vi) How likely is the consumer to exercise care when purchasing the products in question?
(vii) What was the defendant’s intent in selecting the mark?
(viii) How likely are the product lines to expand?