2.106—Answer.
(b)
(1)
An answer shall state in short and plain terms the applicant's defenses to each claim asserted and shall admit or deny the averments upon which the opposer relies. If the applicant is without knowledge or information sufficient to form a belief as to the truth of an averment, applicant shall so state and this will have the effect of a denial. Denials may take any of the forms specified in Rule 8(b) of the Federal Rules of Civil Procedure. An answer may contain any defense, including the affirmative defenses of unclean hands, laches, estoppel, acquiescence, fraud, mistake, prior judgment, or any other matter constituting an avoidance or affirmative defense. When pleading special matters, the Federal Rules of Civil Procedure shall be followed. A reply to an affirmative defense need not be filed. When a defense attacks the validity of a registration pleaded in the opposition, paragraph (b)(2) of this section shall govern. A pleaded registration is a registration identified by number and date of issuance in an original notice of opposition or in any amendment thereto made under Rule 15, Federal Rules of Civil Procedure.
(2)
(i)
A defense attacking the validity of any one or more of the registrations pleaded in the opposition shall be a compulsory counterclaim if grounds for such counterclaim exist at the time when the answer is filed. If grounds for a counterclaim are known to the applicant when the answer to the opposition is filed, the counterclaim shall be pleaded with or as part of the answer. If grounds for a counterclaim are learned during the course of the opposition proceeding, the counterclaim shall be pleaded promptly after the grounds therefor are learned. A counterclaim need not be filed if it is the subject of another proceeding between the same parties or anyone in privity therewith.
(ii)
An attack on the validity of a registration pleaded by an opposer will not be heard unless a counterclaim or separate petition is filed to seek the cancellation of such registration.
(iii)
The provisions of §§ 2.111 through 2.115, inclusive, shall be applicable to counterclaims. A time, not less than thirty days, will be designated within which an answer to the counterclaim must be filed.
(iv)
The times for pleading, discovery, testimony, briefs or oral argument will be reset or extended when necessary, upon motion by a party, to enable a party fully to present or meet a counterclaim or separate petition for cancellation of a registration.
(c)
The opposition may be withdrawn without prejudice before the answer is filed. After the answer is filed, the opposition may not be withdrawn without prejudice except with the written consent of the applicant or the applicant's attorney or other authorized representative.