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*********************************************** 
ELANA GERSHON v. RONALD BACK

(SC 20599)

McDonald, D’Auria, Mullins, Ecker and Alexander, Js.

Syllabus

The plaintiff, whose marriage to the defendant previously had been dissolved

by a New York court, appealed to the Appellate Court from the judgment

of the trial court, which dismissed her motion to open and set aside

the final New York judgment of divorce for lack of subject matter

jurisdiction. Before their marriage, the parties entered into a prenuptial

agreement, pursuant to which the plaintiff waived her interest in certain

of the defendant’s business interests. During the divorce proceedings,

the plaintiff challenged the enforceability of the prenuptial agreement,

but the New York court rejected the claim, finding no evidence of fraud

or overreaching by the defendant. The parties eventually settled their

dispute by way of a separation agreement, which superseded the prenuptial agreement and resolved the parties’ respective financial and property

rights. The separation agreement also included a choice of law provision,

which designated New York law as governing the agreement, and a

provision incorporating New York’s plenary action rule, which requires

a party seeking to modify or vacate a separation agreement that survives

a final judgment of divorce to file a plenary action on the contract

instead of a motion to open, modify or vacate the divorce judgment.

The final judgment of divorce incorporated the separation agreement

by reference but provided that the separation agreement would survive

and not be merged into the judgment. The parties both later moved

to Connecticut, where the plaintiff registered the New York divorce

judgment pursuant to statute (§ 46b-71 (a)). Thereafter, the plaintiff

moved to open and set aside the divorce judgment in the Superior

Court, claiming that it was obtained through the defendant’s fraudulent

conduct. The plaintiff requested that the Connecticut court open the

New York divorce judgment and vacate the settlement agreement.

Applying New York law, the trial court concluded that, because the

separation agreement was incorporated but not merged into the divorce

judgment, the plaintiff could not challenge the enforceability of the

agreement by way of a motion but, rather, was required to do so by

commencing a plenary action. The trial court then dismissed the plaintiff’s motion for lack of subject matter jurisdiction and rendered judgment for the defendant. The Appellate Court agreed with the trial court

that New York’s plenary action rule was substantive for choice of law

purposes but disagreed with the trial court’s conclusion that the trial

court lacked subject matter jurisdiction, relying on, among other things,

the jurisdiction conferred by § 46b-71 (b). Accordingly, the Appellate

Court concluded that the trial court should have denied, rather than

dismissed, the plaintiff’s motion to open and set aside the divorce judgment. On the granting of certification, the plaintiff appealed to this court

from the Appellate Court’s judgment.

Held that the Appellate Court correctly concluded that the New York plenary

action rule is substantive, and not procedural, for choice of law purposes

and that the trial court should have denied, rather than dismissed, the

plaintiff’s motion to open and set aside the divorce judgment:

Under the conflict of law rules governing foreign matrimonial judgments

registered in Connecticut, as codified in § 46b-71 (b), the plaintiff’s

motion to open and set aside the divorce judgment was governed by

New York substantive law and Connecticut procedural law, and that

approach was consistent with the well established principle that, in a

choice of law situation, the forum state will apply its own rules to

issues of procedure and matters of judicial administration, even if the

substantive law of another jurisdiction applies, because it would often

be disruptive or difficult to apply the local rules of another state.

Although New York’s plenary action rule, which is principally concerned

with preserving the parties’ vested contractual rights to enforce the

separation agreement in a separate civil action, fell into a gray area
between issues relating primarily to judicial administration and those

concerned primarily with the rights and liabilities of the parties, this

court concluded that the plenary action rule was so interwoven with

the plaintiff’s cause of action as to be deemed substantive for choice of

law purposes.

The fact that the parties explicitly incorporated the New York plenary

action rule into the separation agreement, which provided that their

contractual rights could not be invalidated or otherwise affected by any

final judgment of divorce, was a weighty reason for applying that law

rather than the local law of the forum, insofar as it demonstrated that

the issue was one to which the parties had likely given thought.

Moreover, the application of the New York plenary action rule would

affect the ultimate substantive outcome of the case because the parties

had contractual rights that could not be undone by modifying the divorce

judgment, there was, to this court’s knowledge, no settled precedent

classifying the plenary action rule as procedural or substantive for choice

of law purposes, and the application of that rule would not impose

an undue burden on Connecticut courts, which have recognized that

separation agreements are contracts that may be litigated independently

of a divorce judgment in a civil action sounding in contract.

Argued October 13, 2022—officially released February 21, 2023

Procedural History

Motion by the plaintiff to open a foreign judgment

of dissolution, brought to the Superior Court in the

judicial district of Stamford-Norwalk, where the court,

Hon. Michael E. Shay, judge trial referee, dismissed

the plaintiff’s motion, and the plaintiff appealed to the

Appellate Court, Lavine, Bright and Beach, Js., which

reversed the judgment of the trial court and remanded

the case with direction to deny the motion, from which

the plaintiff, on the granting of certification, appealed

to this court. Affirmed.

James P. Sexton, with whom were Julia K. Conlin

and, on the brief, John R. Weikart, for the appellant

(plaintiff).

Kenneth J. Bartschi, with whom were Karen L. Dowd

and, on the brief, Wesley W. Horton and Joseph T.

O’Connor, for the appellees (defendants).
Opinion

ECKER, J. New York’s so-called ‘‘plenary action rule’’

requires a party seeking to modify or vacate a separation

agreement that survives a final judgment of divorce to

file a plenary action on the contract instead of a motion

to open, modify or vacate the divorce judgment. This

certified appeal requires us to determine whether New

York’s plenary action rule is procedural or substantive

for choice of law purposes. The trial court concluded

that the rule was substantive and dismissed for lack

of subject matter jurisdiction the motion, filed by the

plaintiff, Elana Gerson, to open and set aside the final

judgment of divorce. The Appellate Court agreed that

the New York rule was substantive but disagreed that

the trial court lacked subject matter jurisdiction and,

therefore, concluded that the plaintiff’s motion should

have been denied instead of dismissed. Gershon v. Back,

201 Conn. App. 225, 253–54, 242 A.3d 481 (2020). We

affirm the judgment of the Appellate Court.

This case has a long and contentious history. The

plaintiff and the defendant, Ronald Back,1 were married

on August 16, 1997. Prior to their marriage, the parties

entered into a prenuptial agreement, pursuant to which

the plaintiff waived her interest in the defendant’s separate property, including his business interest in Flavormatic Industries (Flavormatic). During their marriage, the parties resided in New York and had two

children. In February, 2009, the parties separated, and

the plaintiff commenced a divorce action in the New

York Supreme Court (New York court). The plaintiff

challenged the enforceability of the prenuptial agreement, but the New York court rejected the plaintiff’s

claim, finding that she ‘‘had presented no evidence

establishing that the prenuptial agreement was procured by the defendant’s fraud or overreaching.’’ (Emphasis omitted; internal quotation marks omitted.)

In April, 2011, during their divorce trial, the parties

settled their dispute by entering into a ‘‘[s]tipulation of

[s]ettlement and [a]greement’’ (separation agreement),

which superseded the prenuptial agreement and resolved

the parties’ ‘‘respective financial and property rights,

support, and all other respective rights, remedies, privileges and obligations to each other, arising out of the

marriage . . . .’’ Pursuant to the separation agreement,

the parties agreed to keep their own separate property

and the income and appreciation thereof ‘‘free from any

claim whatsoever from the other party.’’ Additionally,

the parties agreed to waive their respective rights to

each other’s retirement accounts and to divide the proceeds of the sale of the marital residence. The defendant

also agreed to pay the plaintiff $400,000 ‘‘[a]s further

equitable distribution of the parties’ assets . . . .’’ The

separation agreement contains a choice of law provision, which provides that ‘‘[a]ll matters affecting the

execution, interpretation, performance and enforce-
ment of this [a]greement and the rights of the parties

hereto shall be governed by the laws of the [s]tate of

New York.’’

The separation agreement incorporates New York’s

plenary action rule by explicitly providing that it ‘‘shall

not be invalidated or otherwise affected by any decree

or judgment of separation or divorce made by any court

in any action [that] may presently exist or may hereafter

be instituted by either party against the other for a separation or divorce, and the obligations and covenants of

this [a]greement shall survive any decree or judgment

of separation or divorce and shall not merge therein,

and this [a]greement may be enforced independently

of such decree or judgment.’’ The separation agreement

also states that ‘‘[b]oth parties agree, stipulate and consent that no judgment, order or decree in any action

for divorce or separation, whether brought in the [s]tate

of New York, or in any other state or country having

jurisdiction [over] the parties hereto, shall make any

provisions for alimony or child support or affect the

property rights of either party in a manner inconsistent

with the provisions of this [a]greement, but if any provision is made in any judgment, order or decree which

is inconsistent with the provisions of this [a]greement,

or imposes a different or greater obligation on either

of the parties hereto than provided in this [a]greement,

the provisions of this [a]greement shall take precedence

and shall be the primary obligation of both of the parties

hereto. It is further agreed that upon the trial of any

action [that] may hereafter be instituted by either of

the parties against the other for an absolute divorce in

any court of competent jurisdiction, the party instituting

such action shall read the provisions of this [a]greement

relating to maintenance and support into the record of

such action as a stipulation between the parties as to

the questions of maintenance and support. Such party

shall further request that the decree shall contain a

provision specifically reciting, in words or substance,

‘said [a]greement is not merged in, but survives this

decree, and the parties thereof are hereby ordered to

comply with it on its terms at all times and places.’ ’’

On May 11, 2011, the New York court dissolved the

parties’ marriage in a final judgment of divorce, which

incorporated the separation agreement by reference but

provided that the separation agreement ‘‘shall survive

and shall not be merged in this judgment . . . .’’ The

judgment of divorce further stated that ‘‘jurisdiction

over all matters affecting the execution, interpretation,

performance and enforcement of this judgment [and/or]

the [separation agreement] . . . shall be as specifically

provided by the parties’ [separation agreement].’’

The plaintiff remarried three days later and moved

to Greenwich with her new husband and the parties’

children. The defendant later remarried and moved to

Connecticut, as well. On October 27, 2014, the plaintiff
registered the final judgment of divorce in the Superior

Court in the judicial district of Stamford-Norwalk pursuant to General Statutes § 46b-71.2

Extensive litigation in the Superior Court followed.

In November, 2014, the plaintiff moved to modify the

judgment to increase the defendant’s child support obligations, arguing that ‘‘there has been a substantial

change in circumstances since the date of judgment in

that three years have passed since the order was entered

. . . and the defendant’s income has increased by at

least [15] percent . . . .’’3

In connection with this

motion, the plaintiff obtained discovery regarding the

defendant’s finances for the three years preceding the

filing of the motion. Following full disclosure of the

parties’ respective finances, the trial court granted the

plaintiff’s motion, increased the defendant’s child support obligation, and awarded the plaintiff attorney’s

fees.

After the trial court’s order issued, there was a flurry

of further litigation, including motions for reargument

filed by both parties, the defendant’s motion to offset

his child support obligation with a credit for college

room and board expenses, and the plaintiff’s motions

for contempt due to the defendant’s failure to pay the

retroactive amount of his increased child support obligation and the plaintiff’s attorney’s fees. The trial court

denied the motions for reargument, granted the defendant’s motion for a credit, and denied the plaintiff’s

motions for contempt.

The plaintiff then filed a motion to open and set aside

the divorce judgment, which is the operative motion at

issue in this appeal. In her motion, the plaintiff claimed

that she had learned during the modification proceeding

that the divorce judgment ‘‘was obtained through the

fraudulent conduct of the defendant’’ in that he ‘‘made

material misrepresentations of fact to the court and to

the plaintiff in his sworn financial statement provided

at the time of the settlement.’’ Specifically, referring to

the defendant’s ‘‘[a]ttached 2010 [i]ncome [i]nformation,’’ the plaintiff alleged that the defendant’s sworn

statement of net worth dated April 1, 2011, listed his

gross income for the year 2011 as ‘‘0.00,’’ even though

his W-2 form reported wages from Flavormatic in the

amount of $1,900,000 in 2011.4

(Emphasis omitted; internal quotation marks omitted.) The plaintiff further alleged

that the defendant ‘‘stockpiled money in his corporation

in order to avoid equitable distribution of marital assets

and to avoid paying alimony and child support.’’ (Emphasis omitted.) According to the plaintiff, ‘‘there is a reasonable probability that the result of the settlement

would have been different had the defendant not made

material misrepresentations of fact . . . .’’ The plaintiff’s motion asked the court to open the final judgment

of divorce, to vacate the settlement agreement, to order

a new trial, and to award the plaintiff attorney’s fees.
In an accompanying memorandum of law, the plaintiff

requested postjudgment discovery, arguing that she had

met her burden under Oneglia v. Oneglia, 14 Conn. App.

267, 540 A.2d 713 (1988), of demonstrating sufficient

indicia of fraud to justify opening the judgment and

conducting further discovery. See id., 270 (plaintiff was

permitted to conduct postjudgment discovery if she

‘‘was able to substantiate her allegations of fraud beyond

mere suspicion’’).

The defendant opposed the plaintiff’s motion to open,

arguing that the plaintiff had failed to state a claim for

fraud or misrepresentation under New York law because

the defendant’s 2011 statement of net worth was not

inaccurate. The defendant explained that his ‘‘income

for 2011 could not be listed in March of 2011, [because]

over 75 percent of the year remained,’’ and, instead,

‘‘[a]s properly and plainly stated in the statement of net

worth, [the defendant] listed his total income for 2010

[because] that was the last full year of income avail

able.’’ (Emphasis omitted.) The defendant further claimed

that (1) the plaintiff was collaterally estopped from

litigating the issue of the defendant’s net worth because

she ‘‘was provided with substantial discovery regarding

[the defendant’s] businesses during the divorce action’’

and previously had claimed in that action, prior to its

settlement, that the defendant was stockpiling income

in Flavormatic, (2) the plaintiff ratified the separation

agreement by accepting the benefits of the agreement

for more than seven years, and (3) the plaintiff’s motion

was untimely under the New York statute of limitations

governing claims of fraud.

The trial court conducted a three day evidentiary

hearing pursuant to Oneglia to determine whether the

plaintiff could substantiate her allegations of fraud to

a sufficient degree to allow postjudgment discovery. At

the hearing, the trial court heard testimony from the

defendant, the plaintiff, and the plaintiff’s expert witness in forensic accounting, who testified regarding the

defendant’s income and retained earnings in Flavormatic

for the year 2011.

Following the hearing, the trial court issued a memorandum of decision, denying the plaintiff’s request for

postjudgment discovery. The trial court concluded that

the choice of law provision in the separation agreement

‘‘was arrived at without any fraud or duress, and with

the advice of counsel, [that] it should be given effect,’’

and, therefore, that New York law ‘‘relating to postjudgment discovery in matrimonial cases . . . should ultimately control and not Oneglia . . . .’’ The court

observed that, in New York, postjudgment discovery is

not permitted unless there is ‘‘an affirmative, factual

showing, at least prima facie, that the agreement was

unfair or unreasonable when executed or unconscionable at the time of the [rendering] of final judgment.’’

(Emphasis omitted; internal quotation marks omitted.)
Applying this standard, the court concluded that the

plaintiff had ‘‘failed to meet her burden, with at least

a prima facie showing, either that the [separation agreement] was unfair or unreasonable when negotiated, or

unconscionable when the [divorce] judgment was [rendered], or that the defendant’s actions amounted to

wilful fraud or fraudulent concealment. Moreover, she

has not established that, even if the judgment were to

be opened and the [separation agreement] were to be

set aside . . . that the resulting judgment would likely

be substantially different,’’ reasoning that (1) the New

York court had sustained the validity of the parties’

prenuptial agreement, finding no evidence of fraud or

overreaching, (2) under the prenuptial agreement, the

‘‘ ‘operative event’ ’’ for purposes of the division of marital property was the filing of the complaint for divorce

in February, 2009, and, therefore, ‘‘the relevant income

[was] not the defendant’s income for 2011 but, rather,

that of the years 2004 through 2008,’’ (3) the large

increase in the defendant’s income following the rendering of the final judgment of divorce in 2011 was not the

product of ‘‘fraud or fraudulent intent on the part of

the defendant’’ but plausible business decisions, and

(4) ‘‘the plaintiff has accepted the benefit of the agreement for more than three years and, by so doing, ‘effectively ratified’ it, and she should be estopped from challenging it on the basis of fraud.’’

Having determined that the plaintiff was not entitled

to postjudgment discovery, the trial court addressed

New York law regarding the finality of judgments ‘‘in

family relations matters, [when] the judgment is based

[on] an agreement of the parties.’’ The trial court considered it critically important that the separation agreement was incorporated but not merged into the final

judgment of divorce, pointing out that, in New York,

‘‘[i]t is well settled that a party to a stipulation that is

incorporated but not merged into a judgment of divorce

cannot challenge the enforceability of the stipulation

by way of a motion but, rather, must do so by commencement of a plenary action.’’ The trial court ordered

the parties to show cause why the plaintiff’s motion to

open and set aside the judgment ‘‘should not be denied

consistent with New York law.’’

The trial court entertained oral argument on its order

to show cause, after which it dismissed the plaintiff’s

motion for lack of subject matter jurisdiction. The court

explained that, under New York law, a final judgment

of divorce ‘‘cannot [be] attack[ed] . . . based on a

motion to open. It must be done by a plenary action, a

contract action . . . .’’ Accordingly, the court rendered

judgment in favor of the defendant.

The plaintiff appealed from the judgment of the trial

court to the Appellate Court, claiming, among other

things, that the trial court improperly had applied ‘‘New

York procedural rules, rather than Connecticut proce-
dural rules, when it dismissed [her] motion.’’5 Gershon

v. Back, supra, 201 Conn. App. 227. The Appellate Court

disagreed, holding that ‘‘the New York rule requiring a

plenary action to challenge the terms of a settlement

agreement, incorporated but not merged into the judgment of dissolution, is substantive [for choice of law

purposes].’’ Id., 249. The Appellate Court reasoned that,

under New York law, ‘‘[a] stipulation of settlement not

merged into the judgment is independently binding on

the parties, and New York courts may not impair the

parties’ contractual rights under the agreement by modifying the divorce judgment.’’ Id., 251. Because New York’s

plenary action rule ‘‘affects the very existence of the cause

of action,’’ the Appellate Court concluded that it was ‘‘substantive and not procedural.’’ Id., 253.

Although the Appellate Court agreed ‘‘with the [trial]

court’s conclusion that, under New York substantive

law, the plaintiff was required to bring a plenary action’’;

id.; it disagreed ‘‘with the [trial] court’s conclusion that

it lacked subject matter jurisdiction.’’ Id., 254. The

Appellate Court observed that the trial ‘‘court had jurisdiction to consider the motion to open pursuant to

[General Statutes] §§ 46b-1 and 46b-71 (b)’’ and, therefore, concluded that the trial court ‘‘should have denied,

rather than dismissed, the motion to open.’’ Id. We subsequently granted the plaintiff’s petition for certification

to appeal, limited to the following issue: ‘‘Did the Appellate Court correctly determine that a New York law is

substantive rather than procedural for choice of law

purposes when that law would require a litigant in the

parties’ circumstances who is seeking to obtain postjudgment relief in a marital dissolution case to file a

plenary action rather than a motion to open the dissolution judgment?’’ Gershon v. Back, 337 Conn. 901, 901–

902, 252 A.3d 364 (2021).

On appeal to this court, the plaintiff claims that New

York’s plenary action rule is procedural for choice of

law purposes and, therefore, inapplicable to this Connecticut action because it merely designates the means

by which to vindicate her common-law contractual

rights. The defendant responds that New York’s plenary

action rule is substantive because the parties’ commonlaw contractual rights under the separation agreement

are independent of the divorce judgment, and an order

opening, modifying, or vacating the divorce judgment

cannot affect those rights.6 For the reasons that follow,

we agree with the defendant.

‘‘It is well settled that [c]hoice of law questions are

subject to de novo review.’’ (Internal quotation marks

omitted.) Reclaimant Corp. v. Deutsch, 332 Conn. 590,

599, 211 A.3d 976 (2019). To determine whether New

York or Connecticut law governs a motion to open

and vacate a New York judgment of divorce registered

pursuant to § 46b-71, we apply Connecticut’s conflict

of law rules. See id. Subsection (b) of § 46b-71 codifies
the conflict of law rules governing a foreign matrimonial

judgment registered in this state and provides in relevant part that such a judgment ‘‘shall have the same

effect and may be enforced or satisfied in the same

manner as any like judgment of a court of this state

and is subject to the same procedures for modifying,

altering, amending, vacating, setting aside, staying or

suspending said judgment as a judgment of a court of

this state; provided, in modifying, altering, amending,

setting aside, vacating, staying or suspending any such

foreign matrimonial judgment in this state the substantive law of the foreign jurisdiction shall be controlling.’’

The plaintiff’s motion to open and set aside the judgment is governed by New York substantive law and

Connecticut procedural law.

This approach is consistent with the Restatement

(Second) of Conflict of Laws and the well established

principle that, ‘‘in a choice of law situation the forum

state will apply its own procedure . . . .’’ (Internal quotation marks omitted.) Reclaimant Corp. v. Deutsch,

supra, 332 Conn. 603. As we explained in Reclaimant

Corp., under § 122 of the Restatement (Second), ‘‘ ‘[t]he

forum has compelling reasons for applying its own

rules’ to procedural issues, even if the substantive law

of another jurisdiction applies, because, ‘in matters of

judicial administration, it would often be disruptive or

difficult . . . to apply the local rules of another state.

The difficulties involved in doing so would not be repaid

by a furtherance of the values that the application of

another state’s local law is designed to promote.’ ’’ Id.,

604, quoting 1 Restatement (Second), Conflict of Laws

§ 122, comment (a), p. 350 (1971).

The line between substance and procedure is not

always easily drawn. ‘‘[Although] there is no precise

definition of either [substantive or procedural law], it

is generally agreed that a substantive law creates,

defines and regulates rights [whereas] a procedural law

prescribes the methods of enforcing such rights or

obtaining redress.’’ (Internal quotation marks omitted.)

Weber v. U.S. Sterling Securities, Inc., 282 Conn. 722,

739, 924 A.2d 816 (2007). Although procedural rules

generally ‘‘relate to the remedy as distinguished from

the right,’’ we have recognized that some rules are ‘‘so

interwoven with . . . the cause of action as to become

one of the congeries of elements necessary to establish

the right . . . .’’ (Internal quotation marks omitted.)

Reclaimant Corp. v. Deutsch, supra, 332 Conn. 604–605;

see Thomas Iron Co. v. Ensign-Bickford Co., 131 Conn.

665, 669, 42 A.2d 145 (1945) (foreign law is substantive

when ‘‘the foreign remedy is so inseparable from the

cause of action that it must be enforced to preserve

the integrity and character of the cause [of action]’’

(internal quotation marks omitted)). Section 122 of the

Restatement (Second) eschews ‘‘unthinking adherence’’

to formal labels such as ‘‘ ‘procedural’ ’’ and ‘‘ ‘substantive,’ ’’ and, instead, suggests that courts ‘‘face directly the
question whether the forum’s rule should be applied.’’

1 Restatement (Second), supra, § 122, comment (b), p.

352. To determine whether the forum’s rule should be

applied to rules that ‘‘fall into a gray area between issues

relating primarily to judicial administration and those

concerned primarily with the rights and liabilities of the

parties,’’ § 122 instructs courts to consider the following

factors: (1) ‘‘whether the issue is one to which the

parties are likely to have given thought in the course

of entering into the transaction’’; (2) ‘‘whether the issue

is one [the] resolution [of which] would be likely to

affect the ultimate result of the case’’; (3) ‘‘whether

the precedents have tended consistently to classify the

issue as ‘procedural’ or ‘substantive’ for [choice of law]

purposes’’; and (4) ‘‘whether an effort to apply the rules

of the judicial administration of another state would

impose an undue burden [on] the forum.’’ Id., comment

(a), pp. 351–52.

With these principles in mind, we turn to New York’s

plenary action rule and the principles on which it is

based. Unlike Connecticut courts, New York courts do

not review the provisions of a separation agreement to

ensure that the agreement is fair and equitable to the

parties prior to rendering a final judgment of divorce.

Compare N.Y. Dom. Rel. Law § 236 (3) (McKinney Cum.

Supp. 2021) (‘‘[a]n agreement by the parties, made

before or during the marriage, shall be valid and

enforceable in a matrimonial action if such agreement

is in writing, subscribed by the parties, and acknowledged or proven in the manner required to entitle a

deed to be recorded’’), with General Statutes § 46b-66

(a) (court presented with separation agreement ‘‘shall

inquire into the financial resources and actual needs

of the parties . . . in order to determine whether the

agreement of the parties is fair and equitable under all

the circumstances’’). Whereas, in Connecticut, separation agreements typically are merged into the final judgment of divorce after they have been approved by the

court, in New York, separation agreements typically are

not merged but, instead, survive the judgment.

One reason why separation agreements typically are

not merged into the final judgment of divorce in New

York is to avoid placing the imprimatur of the court on

the agreement and ‘‘misleading spouses into believing

[that] such [agreements have been determined] to be

valid . . . .’’ (Citation omitted.) Jaslow v. Jaslow, 75

App. Div. 2d 876, 878, 427 N.Y.S.2d 292 (1980). The

principal reason for this practice, however, is to preserve the contractual rights of the parties to enforce

the separation agreement in a separate civil action. An

unmerged ‘‘separation agreement continues in effect as

a separate and independent contractual arrangement

between the parties . . . . Thus, a change in the divorce

decree cannot modify the separation agreement absent

a clear expression by the parties of such an intent.’’

(Citations omitted.) Kleila v. Kleila, 50 N.Y.2d 277, 283,
406 N.E.2d 753, 428 N.Y.S.2d 896 (1980). The unmerged

separation agreement ‘‘survives as a separate contract

to which the parties are bound. Consequently, [although]

a judgment of divorce can be attacked [by a postjudgment motion], the separation agreement will remain

unimpeached unless challenged in a plenary action

. . . .’’ (Citation omitted.) Lambert v. Lambert, 142

App. Div. 2d 557, 558, 530 N.Y.S.2d 223 (1988); see Fine

v. Fine, 191 App. Div. 2d 410, 411, 594 N.Y.S.2d 309

(1993) (‘‘The stipulation of settlement is an independent

contract binding on the parties . . . and the court may

not impair the plaintiff’s contractual rights under the

agreement by modifying the divorce judgment . . . .

The proper manner for the defendant to challenge the

terms of the stipulation of settlement is in a plenary

action . . . .’’ (Citations omitted.)). In a plenary contract action, the separation agreement is ‘‘subject to

principles of contract construction and interpretation’’;

(internal quotation marks omitted) In re Blonder v.

Blonder, 171 App. Div. 3d 1043, 1045, 98 N.Y.S.3d 329

(2019); instead of the principles governing divorce

actions. See N.Y. Dom. Rel. Law § 236 (3) (McKinney

Cum. Supp. 2021); see also Fine v. Fine, 26 App. Div.

3d 406, 407, 810 N.Y.S.2d 211 (2006) (‘‘[a] plenary action

to vacate a stipulation of settlement on the basis of

fraud . . . is not a matrimonial action’’ under New

York Domestic Relations Law). Stated simply, the parties to an unmerged separation agreement have ‘‘vested

contractual rights’’ that generally cannot be disturbed

by a postjudgment motion in a divorce action.7 Kleila

v. Kleila, supra, 284.

The plenary action rule is predicated, at least in significant part, on New York’s strong public interest in the

finality of judgments; see, e.g., Teitelbaum Holdings,

Ltd. v. Gold, 48 N.Y.2d 51, 55–56, 396 N.E.2d 1029, 421

N.Y.S.2d 556 (1979); and in encouraging parties to resolve

their own interests through contractual arrangements.

See, e.g., Bloomfield v. Bloomfield, 97 N.Y.2d 188, 193,

764 N.E.2d 950, 738 N.Y.S.2d 650 (2001) (‘‘there is a

strong public policy favoring individuals ordering and

deciding their own interests through contractual arrangements’’ (internal quotation marks omitted)); Christian

v. Christian, 42 N.Y.2d 63, 71–72, 365 N.E.2d 849, 396

N.Y.S.2d 817 (1977) (‘‘Generally, separation agreements

[that] are regular on their face are binding on the parties,

unless and until they are put aside . . . . Judicial

review is to be exercised circumspectly, sparingly and

with a persisting view to the encouragement of parties

[to settle] their own differences in connection with the

negotiation of property settlement provisions.’’ (Citations omitted.)); Galusha v. Galusha, 116 N.Y. 635, 645–

46, 22 N.E. 1114 (1889) (‘‘the separation agreement was

not affected by the decree granting an absolute divorce,’’

in part because ‘‘[t]he law looks favorably [on] and

encourages settlements made outside of [the] courts

between parties to a controversy’’). As the New York
Court of Appeals has observed, ‘‘[t]o rewrite a judgment

of divorce [that] has been relied on by both parties . . .

would defeat the [parties’] reasonable expectation that

the judgment was valid as [rendered], and would subvert the policy of upholding settled domestic relations

that underlies the doctrine of equitable estoppel in

divorce cases . . . .’’ (Citations omitted.) Rainbow v.

Swisher, 72 N.Y.2d 106, 110–111, 527 N.E.2d 258, 531

N.Y.S.2d 775 (1988). Because ‘‘the provisions of a

divorce judgment are considered final and binding on

the parties . . . absent unusual circumstances or

explicit statutory authorization’’; (internal quotation

marks omitted) Sass v. Sass, 276 App. Div. 2d 42, 46,

716 N.Y.S.2d 686 (2000); see footnote 7 of this opinion;

an unmerged separation agreement cannot be

rescinded, vacated, or set aside by a postjudgment

motion in a divorce action.

Application of the four factors enumerated in comment (a) to § 122 of the Restatement (Second) leads

us to conclude that New York’s plenary action rule is

so interwoven with the plaintiff’s cause of action as

to be deemed substantive. To begin, the unequivocal

language employed by the parties in their separation

agreement adopted in plain and forceful terms the very

essence of New York’s plenary action rule. In addition

to the choice of law provision’s adoption of New York

law for ‘‘[a]ll matters affecting the execution, interpretation, performance and enforcement of [the separation]

[a]greement and the rights of the parties hereto,’’ the

separation agreement expressly provides that it ‘‘shall

not be invalidated or otherwise affected by any decree

or judgment of separation or divorce made by any

court in any action which may presently exist or may

hereafter be instituted by either party against the other

for a separation or divorce,’’ and adds—if that were

not clear enough—that ‘‘the obligations and covenants

of this [a]greement shall survive any decree or judgment of separation or divorce and shall not merge

therein, and this [a]greement may be enforced independently of such decree or judgment.’’ (Emphasis

added.) The separation agreement further provides that

‘‘no judgment, order or decree in any action for divorce

or separation, whether brought in the [s]tate of New

York, or in any other state or country having jurisdiction

[over] the parties hereto, shall make any provisions

for alimony or child support or affect the property

rights of either party in a manner inconsistent with

the provisions of this [a]greement . . . .’’ (Emphasis

added.)

The fact that the parties explicitly incorporated New

York’s plenary action rule into their separation agreement by providing that their contractual rights could

not be invalidated or affected by any final judgment of

divorce ‘‘is a weighty reason for applying that law rather

than the local law of the forum . . . .’’ 1 Restatement

(Second), supra, § 122, comment (a), p. 351; see Boyd
Rosene & Associates, Inc. v. Kansas Municipal Gas

Agency, 174 F.3d 1115, 1126 (10th Cir. 1999) (‘‘[b]ecause

parties are empowered to make contractual [choice of

law] provisions, their expectations about the applicability of those [choice of law] provisions are a significant

factor in the determination of whether an issue is substantive or procedural for [choice of law] purposes’’).

The remaining Restatement (Second) factors also

weigh in favor of our conclusion that New York’s plenary action rule is substantive under these circumstances. Application of New York’s plenary action rule

will affect the ultimate substantive outcome of this case

because, as the Appellate Court correctly determined,

the parties ‘‘have contractual rights that . . . cannot

be undone by modifying the judgment of dissolution.’’

Gershon v. Back, supra, 201 Conn. App. 251–52; see,

e.g., Goldman v. Goldman, 282 N.Y. 296, 305, 26 N.E.2d

265 (1940) (modification of divorce judgment ‘‘[did] not

relieve the defendant of any contractual obligation’’

under separation agreement, and ‘‘the plaintiff [could]

still resort to the usual remedies for breach of a contractual obligation’’). Additionally, to our knowledge, there

is no settled precedent classifying New York’s plenary

action rule as procedural or substantive for choice of

law purposes; the parties, at least, have not brought

any such precedent to our attention, and we have found

nothing of assistance in this regard. Nor will the application of the rule impose an undue burden on the courts

of this state. Indeed, Connecticut courts have recognized that separation agreements are contracts that may

be litigated independently of the divorce judgment in

a civil contract action. See, e.g., Friedlander v. Friedlander, 5 Conn. App. 1, 4, 496 A.2d 964 (‘‘a separation

agreement is enforceable in a civil suit on the contract’’), cert. denied, 197 Conn. 812, 499 A.2d 58 (1985);

Freeman v. Freeman, Superior Court, judicial district

of Stamford-Norwalk, Docket No. CV-09-6001789-S

(April 6, 2010) (49 Conn. L. Rptr. 578, 580) (‘‘multiple

Superior Court judges have determined that it is appropriate to litigate a breach of a separation agreement in

a civil action for breach of contract’’ (internal quotation

marks omitted)); Lord v. Lord, Superior Court, judicial

district of Fairfield, Docket No. CV-01-0380279 (August

20, 2002) (33 Conn. L. Rptr. 88, 89) (separation agreements are ‘‘contracts . . . enforced by actions brought

[on] the contracts themselves and the remedies are no

other or different than the remedies provided by law

for the breach of any other contract’’ (internal quotation

marks omitted)). We therefore conclude that New York’s

plenary action rule is substantive and that the Appellate

Court correctly determined that the plaintiff’s motion

to open and vacate the divorce judgment should have

been denied.

The plaintiff contends that New York’s plenary action

rule is procedural under Baxter v. Sturm, Ruger & Co.,

230 Conn. 335, 644 A.2d 1297 (1994), and its progeny
because the right to challenge a contract on the basis

of fraud existed at common law.8 This argument misconstrues our reasoning in the Baxter line of cases. In

Baxter, we addressed whether Connecticut law treats

another state’s statute of repose as substantive or procedural for choice of law purposes. Id., 336. We determined that a statute of repose, like a statute of limitations, ‘‘is considered one of the congeries of elements

necessary to establish the right, and therefore characterized as substantive, only when it applies to a new

right created by statute. . . . In such circumstances,

[t]he time within which the suit must be brought operates as a limitation of the liability itself as created [by

the statute], and not of the remedy alone.’’ (Citations

omitted; emphasis in original; internal quotation marks

omitted.) Id., 340. ‘‘If the right existed at common law,

then the statute of repose is properly characterized as

procedural because it functions only as a qualification

on the remedy to enforce the preexisting right. If, however, the right is newly created by the statute, then the

statute of repose is properly characterized as substantive because the period of repose is so integral a part

of the cause of action as to warrant saying that it qualifie[s] the right.’’ (Internal quotation marks omitted.) Id.,

347; see Reclaimant Corp. v. Deutsch, supra, 332 Conn.

608 (‘‘[u]nder Connecticut’s choice of law rules, the

dispositive inquiry is not whether the statute at issue

properly is characterized as a statute of repose or a

statute of limitations, but whether the nature of the

underlying right that forms the basis of the lawsuit

existed at common law’’ (internal quotation marks omitted)).

Baxter and its progeny are inapposite for the simple

reason that New York’s plenary action rule is not a

statute of limitations or a statute of repose, and the

distinction employed to distinguish between procedure

and substance in that context has no application in the

present case. In fact, the plenary action rule is not a

creature of statute at all but, instead, an entrenched

feature of New York’s common law for the past 100

years. See Yonkers Fur Dressing Co. v. Royal Ins. Co.,

Ltd., 247 N.Y. 435, 446, 160 N.E. 778 (1928) (‘‘Defendants

may be able in an independent suit to upset the settlement for reasons that would invalidate a contract, such

as fraud or [overreaching]. But when a compromise

results in the termination of an action and the execution

of a new agreement giving effect to the settlement, it

cannot be undone in the discretion of the court, on

motion in the action and on conflicting affidavits raising anew the same dispute once settled . . . .’’ (Emphasis added.)). The plenary action rule draws ‘‘its justification from the practical notion that there must ultimately

be an end to litigation’’ and requires ‘‘a plenary suit

. . . [in which] the stipulation [of settlement] relates to

an action [that] has previously terminated.’’ Teitelbaum

Holdings, Ltd. v. Gold, supra, 48 N.Y.2d 55. It is properly
characterized as a limitation on the right to challenge

a separation agreement that is incorporated but not

merged into a final judgment of divorce, rather than a

mere limitation on the remedy, particularly because the

parties explicitly incorporated the plenary action rule

into the terms of their separation agreement and, by

doing so, bargained for vested contractual rights that

survive the final judgment of divorce.

The judgment of the Appellate Court is affirmed.

In this opinion the other justices concurred.

1 The defendant died on December 18, 2020, and the coexecutors of his

estate, Adam Cotumaccio and Pamela Chupka, were substituted as defendants. All references to the defendant in this opinion are to Back.

2 General Statutes § 46b-71 provides: ‘‘(a) Any party to an action in which

a foreign matrimonial judgment has been rendered, shall file, with a certified

copy of the foreign matrimonial judgment, in the court in this state in which

enforcement of such judgment is sought, a certification that such judgment

is final, has not been modified, altered, amended, set aside or vacated and

that the enforcement of such judgment has not been stayed or suspended,

and such certificate shall set forth the full name and last-known address of

the other party to such judgment and the name and address of the court in

the foreign state which rendered such judgment.

‘‘(b) Such foreign matrimonial judgment shall become a judgment of the

court of this state where it is filed and shall be enforced and otherwise

treated in the same manner as a judgment of a court in this state; provided

such foreign matrimonial judgment does not contravene the public policy

of the state of Connecticut. A foreign matrimonial judgment so filed shall

have the same effect and may be enforced or satisfied in the same manner

as any like judgment of a court of this state and is subject to the same

procedures for modifying, altering, amending, vacating, setting aside, staying

or suspending said judgment as a judgment of a court of this state; provided,

in modifying, altering, amending, setting aside, vacating, staying or suspending any such foreign matrimonial judgment in this state the substantive

law of the foreign jurisdiction shall be controlling.’’

3 Under the final judgment of divorce, ‘‘[e]ach party has a right to seek a

modification of the child support order upon a showing of: (i) a substantial

change in circumstances; or (ii) that three years have passed since the order

was entered, last modified or adjusted; or (iii) there has been a change in

either party’s gross income by [15] percent or more since the order was

entered, last modified, or adjusted; however, if the parties have specifically

opted out [of] subparagraph (ii) or (iii) of this paragraph in a validly executed

agreement or stipulation, then that basis to seek modification does not

apply.’’ (Emphasis omitted.) See N.Y. Dom. Rel. Law § 236 (9) (b) (2) (i)

(McKinney Cum. Supp. 2021) (‘‘[t]he court may modify an order of child

support, including an order incorporating without merging an agreement

or stipulation of the parties, upon a showing of a substantial change in

circumstances’’); N.Y. Dom. Rel. Law § 236 (9) (b) (2) (ii) (A) and (B)

(McKinney Cum. Supp. 2021) (‘‘[i]n addition, unless the parties have specifically opted out of the following provisions in a validly executed agreement

or stipulation entered into between the parties, the court may modify an

order of child support where . . . three years have passed since the order

was entered, last modified or adjusted; or . . . there has been a change in

either party’s gross income by fifteen percent or more since the order was

entered, last modified or adjusted’’). In its memorandum of decision on the

plaintiff’s motion for modification, the trial court found that the parties

clearly had not opted out of subparagraphs (ii) or (iii) in the separation

agreement.

4 The defendant’s attached 2010 income information included his W-2 form

from Flavormatic, which listed his wages and earnings as $150,000.

5 The plaintiff also claimed that the trial court ‘‘(1) improperly addressed

the merits of the motion to open after determining that it lacked subject

matter jurisdiction, (2) abused its discretion by failing to grant her motion

for a continuance after her counsel disclosed that she intended to withdraw

her appearance, and (3) erred in finding that the plaintiff had failed to

demonstrate probable cause for postjudgment discovery under Oneglia . . .

or comparable New York law.’’ Gershon v. Back, supra, 201 Conn. App. 227

n.1. The Appellate Court did not address the plaintiff’s additional claims in
light of its conclusion that ‘‘the plaintiff was required to raise her claims

with respect to the parties’ [separation agreement] by means of a plenary

action.’’ Id.

6 The defendant also claims that this certified appeal is moot because the

trial court’s judgment may be affirmed on the alternative ground that the

plaintiff ratified the separation agreement and, therefore, is estopped from

challenging it on the basis of fraud. ‘‘Undoubtedly, if there exists an unchallenged, independent ground to support a decision, an appeal from that

decision would be moot, as this court could not afford practical relief even

if the appellant were to prevail on the issue raised on appeal.’’ Hartford v.

CBV Parking Hartford, LLC, 330 Conn. 200, 210, 192 A.3d 406 (2018). To

render an appeal moot, however, the unchallenged ground must be independent of the issue on appeal, meaning that resolution of the issue on appeal

would not and could not affect a separate unchallenged basis on which to

affirm the underlying judgment. See id., 211–12 (appeal was not moot

because trial court’s factual finding regarding valuation of property was

not independent of issue on appeal). In the present case, the trial court’s

resolution of the ratification issue was not independent of its resolution of

the choice of law question because the trial court’s application of New York

law to the plaintiff’s request for postjudgment discovery led it to conclude

that the plaintiff had produced insufficient evidence of fraud and, therefore,

was estopped from challenging the agreement. See, e.g., Brennan v. Brennan, 305 App. Div. 2d 524, 525, 759 N.Y.S.2d 744 (2003) (concluding that

separation agreement had been ratified in absence of evidence of fraud);

Wilson v. Neppell, 253 App. Div. 2d 493, 494, 677 N.Y.S.2d 144 (same), appeal

denied, 92 N.Y.2d 816, 706 N.E.2d 747, 683 N.Y.S.2d 759 (1998); Shalmoni

v. Shalmoni, 141 App. Div. 2d 628, 629, 529 N.Y.S.2d 538 (same), appeal

dismissed, 73 N.Y.2d 851, 534 N.E.2d 333, 537 N.Y.S.2d 495 (1988); see also

Ronson v. Ronson, 58 App. Div. 2d 987, 988, 396 N.Y.S.2d 939 (1977) (‘‘In

order to vitiate the support agreement, [a party] is required to show facts

in evidentiary form. Conclusory assertions of fraud are insufficient . . . .’’

(Citations omitted.)). Because the choice of law and ratification issues are

related, we conclude that the plaintiff’s appeal is not moot.

7 There are some exceptions to the plenary action rule, none of which is

applicable to the present appeal. See, e.g., N.Y. Dom. Rel. Law § 236 (9) (b)

(1) (McKinney Cum. Supp. 2021) (‘‘[w]here, after the effective date of this

part, an agreement remains in force, no modification of an order or judgment

incorporating the terms of said agreement shall be made as to maintenance

without a showing of extreme hardship on either party, in which event

the judgment or order as modified shall supersede the terms of the prior

agreement and judgment for such period of time and under such circumstances as the court determines’’); N.Y. Gen. Oblig. Law § 5-311 (McKinney

2022) (‘‘Except as provided in section two hundred thirty-six of the domestic

relations law, a husband and wife cannot contract to alter or dissolve the

marriage or to relieve either of his or her liability to support the other in

such a manner that he or she will become incapable of self-support and

therefore is likely to become a public charge. An agreement, heretofore or

hereafter made between a husband and wife, shall not be considered a

contract to alter or dissolve the marriage unless it contains an express

provision requiring the dissolution of the marriage or provides for the procurement of grounds of divorce.’’); N.Y. Jud. Ct. Acts § 463 (McKinney 2008)

(‘‘[a] separation agreement does not preclude the filing of a petition and

the making of an order under section four hundred forty-five of this article

for support of a spouse who is likely to become in need of public assistance

or care’’); see also footnote 3 of this opinion.

8 The plaintiff also contends that the plenary action rule is procedural

because the failure to commence a plenary action is not always treated as

a fatal defect in New York. In support of this contention, the plaintiff relies

on cases from the Appellate Division of the New York Supreme Court that

recognized the plenary action rule but, in the interest of judicial economy,

nonetheless addressed the merits of a postjudgment motion challenging an

unmerged separation agreement when the lower court had conducted ‘‘a

full hearing tantamount to a plenary trial . . . .’’ Gaines v. Gaines, 188 App.

Div. 2d 1048, 1048, 592 N.Y.S.2d 204 (1992); accord Verna v. Verna, 134

App. Div. 3d 1438, 1438, 23 N.Y.S.3d 500 (2015); Dunham v. Dunham, 214

App. Div. 2d 961, 961, 626 N.Y.S.2d 932 (1995); Culp v. Culp, 117 App. Div.

2d 700, 702, 498 N.Y.S.2d 846 (1986). The plaintiff argues that these cases

stand for the proposition that the plenary action rule is procedural because,

‘‘[if] the rule [was] substantive, the court would have [had] no authority’’

to adjudicate the postjudgment motion. We reject the plaintiff’s claim
because there is a fundamental distinction between the authority of a court

to adjudicate a cause of action and the court’s determination of the substantive law governing that cause of action. See Lacks v. Lacks, 41 N.Y.2d 71,

74, 77, 359 N.E.2d 384, 390 N.Y.S.2d 875 (1976). As the New York Court of

Appeals explained in Lacks, the ‘‘[subject matter] jurisdiction-competence’’

of the courts should not be confused with the ‘‘substantive elements of a

cause for relief’’ because ‘‘[t]o do so would be to undermine significantly

the doctrine of res judicata, and to eliminate the certainty and finality in

the law and in litigation which the doctrine is designed to protect.’’ Id., 77.

Thus, the nonjurisdictional nature of the plenary action rule does not resolve

the issue of whether the rule is substantive or procedural for choice of

law purposes.