New York Laws
Article 10 - Action for Divorce
172 - Co-Respondent as Party.

ยง 172. Co-respondent as party. 1. In an action brought to obtain a
divorce on the ground of adultery the plaintiff or defendant may serve a
copy of his pleading on a co-respondent named therein. At any time
within twenty days after such service, the co-respondent may appear to
defend such action so far as the issues affect him. If no such service
be made, then at any time before the entry of judgment a co-respondent
named in any of the pleadings may make a written demand on any party for
a copy of a summons and a pleading served by such party, which must be
served within ten days thereafter, and he may appear to defend such
action so far as the issues affect him.

2. In an action for divorce where a co-respondent has appeared and
defended, in case no one of the allegations of adultery controverted by
such co-respondent shall be proven, such co-respondent shall be entitled
to a bill of costs against the person naming him as such co-respondent,
which bill of costs shall consist only of the sum now allowed by law as
a trial fee, and disbursements.