Initial Five Years: Trademarks are most vulnerable during their first five years. Opposing parties can challenge the mark on broader grounds, including its potential similarity to other marks or lack of distinctiveness.
Post-Five Years: After five years (and before ten), assuming the registrant has filed a Section 15 – “Declaration of Incontestability,” the mark becomes “incontestable.”
If a mark is incontestable, you can only file a cancellation on the following grounds:
- The mark has become a generic term.
- The mark is abandoned (non-use).
- The mark was acquired fraudulently.