The grounds a trademark opposition is built on.
An opposition, and the defence against it, turns on a handful of recognised grounds. These are broadly consistent across India, the US, the UK, and the EU, though the exact wording and burden differ. The same grounds work in reverse when you are defending: each one the opponent raises is one you rebut.
Similarity to an existing mark
The most common ground. The published mark is similar or identical to an earlier registered or pending mark, creating a likelihood of confusion. The defence distinguishes the marks phonetically, visually, and conceptually, and shows different goods, classes, or consumers.
Prior use
The opponent claims they used the mark first, even if unregistered. Prior continuous use carries real weight in common-law systems like India, the US, and the UK. The case lives or dies on dated evidence of who used the mark first and for what.
Lack of distinctiveness
The mark is generic, descriptive, or non-distinctive and should not have been accepted. The defence shows acquired distinctiveness through use, or that the mark is inherently distinctive.
Bad faith
The application was filed in bad faith, for example to squat on a known brand or block a competitor. This ground needs evidence of the applicant’s knowledge and intent.
Well-known and reputed marks
A well-known mark can oppose even across different classes, on the basis that use would take unfair advantage of or damage its reputation. Reputation has to be evidenced, not merely asserted.
The grounds are only half of it. Oppositions are won on the evidence filed to support them, and on knowing when a settlement beats a fight.