Legal Question in Business Law in California

Re: common law as pertaining to trademarks

I did a quick check of California cases on common-law trademarks, and found non discussing the duration or expiration of common-law trademark rights.

A California statutory trademark is good for ten years.

I'd say that a court called upon to decide whether a common-law trademark was still valid would be guided by the facts and circumstances of the particular situation, including the existence of damage or harm to the claimant, whether the use of the other's asserted trademark was truly unfair, whether the notion of a right to compete suggested allowing use of the mark by others, and other such considerations of fairness and equity. A former user of a common-law trademark should not be allowed to tie up the mark when it has clearly stopped using it and no real likelihood of consumer confusion exists any more.

I might add that acquiring a common-law trademark right takes more than just using a phrase on merchandise sold. This is certainly a prerequisite to acquiring a common-law trademark, but may not be enough all by itself, particularly in an attempt to defend the mark against others much later in time.