Any person shown to be interested may become a party to any civil action upon filing and service of an Appearance and pleading briefly setting forth his or her relation to the cause; or, upon motion of any party, such person may be made a party by order of court notifying him or her to appear therein. If a party, so notified, neglects to file an Answer or other responsive pleading on or before the date established by the court, that party shall be defaulted. No such default shall be set aside, except by agreement or by order of the court upon such terms as justice may require.
Rule 15.Intervention
Group IV: Parties and their Representatives · Last amended October 1, 2013 · Last verified July 14, 2026
In one sentenceRule 15 lets a person with an interest in a pending civil action join it either by filing an appearance and a short pleading describing that interest, or by being brought in on a party’s motion and court order, with default consequences for failing to respond once notified.
Full Text of Rule 15
Amendment History
Adopted May 22, 2013, eff. October 1, 2013.
Plain-English Summary
Rule 15 gives an outside party a path into a lawsuit already underway. Anyone who can show an interest in the case may become a party by filing an appearance along with a pleading that briefly explains the connection to the case. Alternatively, an existing party can move the court to bring that person in, and the court can order the person to appear.
Once a person has been notified to appear under this rule, the clock starts running. Failing to file an Answer or other responsive pleading by the court’s deadline results in a default. That default is not easily undone — the rule allows it to be set aside only by the parties’ agreement or by court order on terms that justice requires.
Frequently Asked Questions
How does someone intervene in a New Hampshire civil case?
Under Rule 15, a person with an interest in the case may become a party by filing and serving an Appearance and a pleading briefly setting forth the relation to the case, or a party may move the court to make that person a party by order notifying the person to appear.
What happens if a person notified to appear under Rule 15 doesn’t respond?
The rule provides that a person who neglects to file an Answer or other responsive pleading by the date the court sets will be defaulted.
Can a default entered under Rule 15 be undone?
Only by agreement of the parties or by court order on terms that justice requires. The rule does not allow a default to be set aside on any other basis.
Do I need the court’s permission before intervening in a case?
Not necessarily. A person with an interest can intervene by filing an appearance and a pleading describing that interest. A court order is only needed when another party moves to bring the person in.
What must an intervention pleading contain?
Rule 15 requires the pleading to briefly set forth the intervening person’s relation to the cause of action.
Source & verification. Rule text, official Comments, and amendment
history are reproduced verbatim from the New Hampshire Superior Court Civil Rules, adopted
by the New Hampshire Supreme Court. Last verified July 14, 2026.
· Official source
Also known as: intervention nh superior courthow to intervene in a lawsuit nhjoining a pending lawsuit nhrule 15 nh civil procedure