The adversarial stage in trademark law refers to the stage of an opposition proceeding when the parties present their respective cases and evidence to the trademark office in order to support their positions on the validity or registration of a trademark.
The adversarial stage typically takes place after the Notice of Opposition has been filed and any cooling-off period has ended without a settlement agreement being reached. During this stage, the parties engage in a process similar to a trial, presenting evidence and legal arguments to the trademark office in order to support their respective positions on the trademark registration.
The trademark office will review the evidence and arguments presented by both parties and make a decision on the validity or registration of the trademark based on the legal and factual issues at hand. The trademark office's decision may be appealed by either party to a higher court, depending on the specific jurisdiction and the available avenues for appeal.