                              In the

United States Court of Appeals
               For the Seventh Circuit

No. 11-3602

IAIN W ALKER,
                                                Petitioner-Appellant,
                                  v.

N ORENE W ALKER,
                                                Respondent-Appellee.


             Appeal from the United States District Court
        for the Northern District of Illinois, Eastern Division.
           No. 11 C 2967—Samuel Der-Yeghiayan, Judge.



  A RGUED S EPTEMBER 11, 2012—D ECIDED N OVEMBER 16, 2012




  Before B AUER, P OSNER, and W OOD , Circuit Judges.
   W OOD , Circuit Judge. Iain Walker, a citizen of Australia,
filed this suit under the International Child Abduction
Remedies Act (ICARA), 42 U.S.C. § 11601 et seq., in an
effort to compel his wife, Norene, a citizen of the United
States, to return the couple’s three children to Australia.
ICARA implements the Hague Convention on the Civil
Aspects of International Child Abduction (the Conven-
tion), T.I.A.S. No. 11,670, 1343 U.N.T.S. 89 (Oct. 25, 1980).
2                                             No. 11-3602

The Convention, to which both the United States and
Australia are parties, “entitles a person whose child has
wrongfully been [retained in] the United States . . . to
petition for return of the child to the child’s country of
‘habitual residence,’ unless certain exceptions apply.”
Norinder v. Fuentes, 657 F.3d 526, 529 (7th Cir. 2011).
  The district court denied Iain’s petition. It found that
notwithstanding the fact that the Walker family lived in
Australia from 1998 until 2010, the children’s habitual
residence had become the United States by the time
Iain filed his petition. In addition, as the court saw it,
Norene’s act of keeping the children in the United States
could not have been “wrongful” within the meaning of the
Convention for two reasons: first, Iain was not exercising
his custody rights at the relevant time; and, second, Iain
had consented to the children’s remaining in the United
States permanently. Iain challenges all of these rulings
on appeal. We conclude that the record does not
support the court’s decision and that a remand is neces-
sary before the case can be resolved.


                            I
  Iain and Norene were married in Chicago in 1993.
They lived in Seattle, Washington, until 1998 when they
moved to Perth, in Western Australia. The couple’s
eldest child was born in the United States in 1997, but
lived in this country only one year; the two younger
children were born in Australia in 1999 and 2001.
  Although Norene testified that she and Iain initially
intended to stay in Australia for only five years, they
No. 11-3602                                               3

ended up spending 12 years there. Over this period, they
and their children appeared to be well-settled: they
owned a home, furniture, and a dog named Chubba; the
children attended school, had friends, and participated
in activities; and Iain worked as a software test engineer
while Norene cared for the children.
  In June 2010, the Walkers traveled to the United States.
When they left Australia, both Iain and Norene ex-
pected that Norene and the children would remain in
the United States for six months to one year. There
the common ground ends. According to Iain, the plan
was for Norene and the children to live with Norene’s
parents in Chicago while the family demolished its
existing house in Perth and built a new one. According
to Norene, the trip was intended as an extended prelude
to a permanent move to the United States; she testified
(a bit inconsistently, it seems to us) that Iain promised
to look for a job in Chicago and that they looked at
real estate in San Francisco and Seattle. Although both
recalled that Norene and the children had concrete plans
to return to Australia by June 2011 at the latest, Norene
labeled this most likely a temporary visit and Iain under-
stood it to be a permanent return. After spending
several weeks with Norene and the children in the
United States, Iain returned to Australia in late July 2010.
   As may be apparent, all was not well with the marriage.
In November, Norene filed for divorce in Cook County,
Illinois. As of that time, she said, she had not made up
her mind whether she (and presumably the children)
would remain in the United States permanently or
return to Australia.
4                                                No. 11-3602

  Upon receiving Norene’s petition for divorce, Iain’s
lawyer in Australia sent a letter to Norene’s attorney
offering to settle the divorce out of court. The lawyer
described the letter, which was transmitted on January 21,
2011, as a “once off attempt to have all outstanding
matters resolved.” In it he made, “on a without prejudice
basis,” certain proposals that were expressly conditioned
on Norene’s acceptance of Iain’s offer. For example, in
exchange for granting primary custody to Norene and
allowing the children to remain in the United States, Iain
wanted to be guaranteed custody of the children for the
full nine weeks of their summer vacation and for two
weeks over the Christmas holidays; he further requested
that he be allowed to visit the children in the United
States at least twice a year. The letter also dealt with
the division of property.
   Notably, the letter explicitly referred to the Hague
Convention. On Iain’s behalf, the lawyer asserted that
“[t]he parties’ habitual residence is quite clearly Austra-
lia,” and that Iain “would clearly be entitled to bring
an Application under the Hague Convention to have
the children returned to Australia.” In closing, the letter
stated “this offer is open for a period of 7 days . . . and if
not accepted [Iain] will then proceed to exercise his
full rights pursuant to the Hague Convention, and
do all that is required to ensure that proceedings are
transferred” to the Family Court of the State of Western
Australia.
 The January 21 letter marked a turning point for
Norene. She regarded it as giving her permission to stay
No. 11-3602                                                 5

in the United States and indicating that Iain “didn’t
want the kids.” She testified that shortly after receiving
the letter, she made up her mind not to return to Austra-
lia. Norene did not, however, accept Iain’s offer
of settlement; after an exchange of several more
letters, the negotiations ended without a resolution in
mid-February. Iain immediately filed a request for
the return of the children with the Australian Central
Authority charged with administering the Convention.
In May, Iain filed a petition for return in the district
court for the Northern District of Illinois.
  Following a two-day evidentiary hearing, the district
court denied the petition. This appeal followed.


                              II
                              A
  Before discussing the merits of the district court’s
decision, we must address two preliminary issues. First,
Norene argues that this case was mooted by an Illinois
state-court judgment awarding sole custody of the
children to Norene. According to Norene, the Illinois
judgment conclusively resolves the parties’ custody
dispute in her favor and thus precludes this court from
ruling that the Hague Convention requires the custody
determination to occur in the courts of Australia.
  Norene is mistaken: the case is not moot. Article 17 of
the Hague Convention expressly states that “[t]he sole
fact that a decision relating to custody has been given in
or is entitled to recognition in the requested State shall not
6                                            No. 11-3602

be a ground for refusing to return a child under this
Convention.” (Emphasis added.) This treaty provision
qualifies the finality of any state-court custody judg-
ment and thus ensures that there is still a live con-
troversy before the federal court.
  Norene relies on Navani v. Shahani, 496 F.3d 1121 (10th
Cir. 2007), for the proposition that an order granting
custody to one or another of the parents can moot a
Hague Convention case, but Navani did not speak to
this question. Indeed, the issue of habitual resi-
dence—and thus the question of which country’s courts
had the power finally to determine custody under the
Convention—was not before the court in Navani; all
parties agreed that the child’s habitual residence was
England. Rather, the question on appeal was whether
the U.S. court that adjudicated the father’s petition for
return erred in concluding that an English custody
order granted some custody rights to the father. Id.
at 1125-26. While the appeal was pending, an English
court entered a new custody order that granted the
father sole custody. Id. at 1126. The Tenth Circuit con-
cluded that this superseding custody order mooted the
appeal—both because any possible error in the inter-
pretation of the previous order was no longer of any
moment given the new order, and because relief that
directly conflicted with that ordered by the courts of
the child’s habitual residence would undermine the
Hague Convention’s purpose of allowing those courts
to resolve the parents’ custody disputes. Id. at 1127-29.
  Here, in contrast, Iain and Norene dispute habitual
residence. Until that question is resolved, we cannot say
No. 11-3602                                               7

which country’s courts have the power to resolve the
issue of custody. As Article 17 of the Convention
implies, this antecedent question must be answered
before we know what weight to give to the judgment of
the Illinois court.
   This makes sense, given the purpose of the Convention.
Accepting Norene’s position that an abducting parent
may render a petition for return moot by racing to a
courthouse in her chosen country to obtain a custody
judgment would turn the Convention on its head. The
entire purpose of the Convention is to deter parents
from absconding with their children and crossing inter-
national borders in the hopes of obtaining a favorable
custody determination in a friendlier jurisdiction. See
Elisa Pérez-Vera, Explanatory Report on the 1980 Hague
Child Abduction Convention, in Acts & Documents of
the Fourteenth Session, Vol. 3, 17 (1980). To consider
this case moot would encourage the very sort of jurisdic-
tional gerrymandering the Convention was designed
to prevent. We note as well that courts faced with
similar arguments based on abstention, the Rooker-Feldman
doctrine, and res judicata have held that these doctrines
do not deprive the federal courts of jurisdiction to rule
on the merits of Convention petitions, either in the
first instance or on appeal. See, e.g., Yang v. Tsui, 416
F.3d 199, 201-04 (3d Cir. 2005) (Younger abstention not
appropriate); Silverman v. Silverman, 338 F.3d 886, 894 (8th
Cir. 2003) (Rooker-Feldman doctrine inapplicable); Holder
v. Holder, 305 F.3d 854, 864-66 & 867-72 (9th Cir. 2002)
(res judicata inapplicable; Colorado River abstention inap-
propriate); Mozes v. Mozes, 239 F.3d 1067, 1085 n.55 (9th
8                                             No. 11-3602

Cir. 2001) (Rooker-Feldman doctrine inapplicable). Norene
raises several cursory arguments based on the latter
doctrines; like our sister circuits, we find no merit in
these points.


                            B
  The second preliminary issue concerns the district
court’s decision to admit the January 21 letter into
evidence over Iain’s objection that the letter is an offer
of settlement and thus is inadmissible under Federal
Rule of Evidence 408. Rule 408 says that evidence of
“furnishing or offering or promising to furnish . . . a
valuable consideration in . . . attempting to compromise
the claim” may not be admitted to “prove liability for,
invalidity of, or amount of a claim that was disputed as
to validity or amount.” Iain argues that this language is
broad enough to cover the letter’s use here: the letter
was an offer to compromise the parties’ divorce
dispute; the divorce proceeding included claims over
both property and child custody; and the letter was
being offered to prove the “invalidity” of Iain’s petition
for the return of the children on the theory that he
had waived that right by consenting to Norene’s custody.
   The district court rejected Iain’s argument under
Rule 408 and admitted the letter, however, because in
its view, the divorce and Convention proceedings were
“entirely separate.” The court also believed that Iain
had failed to show that the use of the letter in the Con-
vention case “would impair the settlement process in
the underlying divorce action.”
No. 11-3602                                                9

   This ruling is flawed in at least two respects. First, the
divorce and Convention proceedings are not “entirely
separate.” A decision or action in one proceeding
almost inevitably will have an impact on the other. A
successful petition for return identifies the proper
forum for the custody determination in a divorce case,
and (as the losing parent often fears) the courts of the
habitual residence may be sympathetic to the local
parent’s position. More importantly, although the dis-
trict court was correct to consider Rule 408’s purpose
in deciding whether to admit the letter, see Zurich Am.
Ins. Co. v. Watts Indus., Inc., 417 F.3d 682, 689 (7th Cir.
2005), in focusing on the letter’s potential to impede
settlement in Iain and Norene’s ongoing divorce action,
the district court was looking at the wrong thing.
Rule 408 addresses the concern that a norm of admitting
offers of settlement will reduce efforts to settle by others
in the future; its focus is not on the effect of admitting
an offer of settlement on these parties’ likelihood of set-
tling. Almost by definition, the parties in the present
case have already failed to settle and are now deeply
involved in litigation, and so for them, there is
nothing left to chill.
  When viewed in the proper perspective, there is little
doubt that admitting a document like the January 21
letter has the potential to deter future efforts to settle
international divorce and custody disputes. A parent
in Iain’s situation with an interest in reaching an
out-of-court settlement with his or her spouse would
have no incentive to make an offer without including
some mention of child custody (often the single most
10                                              No. 11-3602

significant issue in a divorce). But if that parent knows
that any offer related to custody may later be relied
upon to find that the parent has abandoned his custody
rights or consented to the child’s remaining abroad,
then that parent will be less willing to make any offer at
all. In our view, the court should have excluded the
letter pursuant to Rule 408.
  That said, we must still consider whether this error
had an effect on the outcome of the case. Since this was
a trial to the court, the contents of the letter were very
likely to come to the judge’s attention anyway: the
court had to read the letter in order to determine
whether it was admissible. At that point, the horse was
effectively out of the barn. In any event, the critical ques-
tion is whether the judge was entitled to give weight to
the letter. He should not have done so. Moreover, as
we explain below, the letter in any event provides no
basis for denying Iain’s petition for return.


                             III
  Iain challenges the district court’s findings that he
(1) failed to establish that the children were habitually
resident in Australia; (2) failed to establish that he was
exercising his custody rights; and (3) consented to the
children remaining permanently in the United States.
Because any one of these findings would suffice to
defeat a petition for return, we must affirm unless we
conclude that the district court reached the wrong con-
clusion on each of them.
No. 11-3602                                               11

                             A
  Everyone agrees that this is not a case of wrongful
removal of the children; it is a case of wrongful reten-
tion. The first question is therefore when the retention
began. The district court identified May 4, 2011, the day
Iain filed his petition for return in the district court,
as the date the retention began. It considered that to be
the date when Iain first “unequivocally signaled h[is]
opposition to [the children’s] presence in the United
States.” Although Iain had expressed his intent to file
a petition for return of the children in the January 21
letter (and again in a follow-up letter on February 16),
the district court declined to view these statements as
“unequivocal[] signal[s]” of opposition because, in the
court’s view, “it was apparent that Petitioner was
referring to the Convention as a bargaining chip.”
   The date on which the wrongful retention commenced
is a question of fact on which we would normally defer
to the district court. See Karkkainen v. Kovalchuk, 445
F.3d 280, 290 (3d Cir. 2006). Here, however, nothing but
speculation supports the district court’s “bargaining
chip” idea. Worse, whether Iain’s mention of the Con-
vention was meant as a “bargaining chip” is irrelevant
to whether Iain signaled his opposition to the children
remaining in the United States in the January 21 letter.
What matters is that the January 21 letter unequivocally
says that “[t]he parties’ habitual residence is quite
clearly Australia.” It goes on to point out that the “clearly
appropriate forum” for the parties’ divorce proceedings
is Australia and that it is “an abuse of process to unilater-
12                                            No. 11-3602

ally decide to remain in the United States.” It then
repeats that “Western Australia is the habitual residence
of the children.” Finally, the letter announces Iain’s
intent to file a petition under the Hague Convention, a
step that he confirmed in his February 16 letter. Under
the circumstances, it is hard to see how much more
“unequivocal” one could be.
   The district court was apparently under the impres-
sion that Iain then did nothing during the five months
between the exchange of letters with Norene and the
filing of the petition for return on May 4, but if so,
it was mistaken. The petition reveals that in mid-
February, Iain filed a request for return with the Cen-
tral Authority in Australia. The Convention provides for
the establishment of Central Authorities (designated
agencies responsible for administering the Convention)
and contemplates that parents will seek their assistance
in obtaining the return of their children. Arts. 6-10.
In Australia, the Central Authority directs parents
seeking return of their children to file a request for re-
turn. See About International Child Abduction, Attorney
General’s Department, Australian Government, http://
www.ag.gov.au/Families/Pages/Internationalfamilylaw/
FAQaboutinternationalparentalchildabduction.aspx#to
(last visited Nov. 13, 2012). That was exactly what Iain
did here. In acting promptly to secure the return of the
children according to procedures approved by both the
Convention and the government of Australia, Iain
properly signaled his opposition to the children’s re-
tention in the United States. For the district court to
conclude that this opposition was not apparent until
No. 11-3602                                                13

May 4 was clear error. Accordingly, for purposes of
our analysis, we assume that the retention began on
January 21, or, at the latest, several weeks thereafter.
  Before moving on, we note our concern with the
district court’s interpretation of the January 21 letter.
The district court inferred that Iain was uninterested in
the children except to the extent that they could be
used as a “bargaining chip” to obtain a more favorable
property settlement. We find nothing in the letter
that supports such a view. Under the Convention, the
merits of Iain and Norene’s custody dispute are
irrelevant to the distinct question whether that dispute
should be resolved by the courts of Australia or the
United States. Arts. 1 & 19; see also Friedrich v. Friedrich,
78 F.3d 1060, 1065 (6th Cir. 1996). Assumptions about
likely motives of either parent also play no part in Con-
vention decisions. As it happens, fathers are far more
likely than mothers to file petitions for return and
access under the Convention. In 2008 (the last year for
which detailed statistics are available), fathers filed
roughly 69% of global applications (and 59% of U.S.
applications) for return and roughly 79% of global ap-
plications (and 73% of U.S. applications) for access. See
Nigel Lowe, A Statistical Analysis of Applications Made in
2008 Under the Hague Convention of October 25, 1980 on
the Civil Aspects of International Child Abduction, Pt. I, 14,
54 (2011); id. at Pt. III, 199, 209. (We say “roughly”
because the Hague Conference on Private International
Law reports statistics on the people against whom
petitions for return are filed, but it does not specifically
report statistics on who files the petitions. Inferring how
14                                             No. 11-3602

many fathers file petitions for return or access is thus
somewhat imprecise. Although in the vast majority of
cases in which a petition is filed against a mother, the
petitioner will be the father, the petitioner could con-
ceivably be a grandparent, other relative, or an institu-
tion as well.)


                            B
  To prevail on his petition, Iain was required to show
that Australia was the children’s habitual residence at
the time of their retention in the United States. We ex-
plained in detail how to determine a child’s habitual
residence in Koch v. Koch, 450 F.3d 703 (7th Cir. 2006). In
a case alleging wrongful retention, we determine a
child’s habitual residence by asking “whether a prior
place of residence . . . was effectively abandoned and a
new residence established . . . ‘by the shared actions
and intent of the parents coupled with the passage of
time.’ ” Norinder, 657 F.3d at 534 (quoting Koch, 450 F.3d
at 715). Because the parents often dispute their inten-
tions, “the court should look at actions as well as dec-
larations” in determining whether the parents “shared
an intent to abandon a prior habitual residence.” Koch,
450 F.3d at 715. In an appeal from a habitual residence
determination, the court reviews findings on the parties’
intent for clear error, while “[t]he ultimate determina-
tion of habitual residence is a mixed question of law and
fact to which we will apply de novo review.” Id. at 710.
  The district court found that the children’s habitual
residence became the United States by January 21, 2011, at
No. 11-3602                                              15

the latest. This conclusion was premised on the fol-
lowing findings: (1) that Iain consented to the
children’s living in the United States in the January 21
letter; (2) that five months passed between the letter
and the filing of the petition for return in district court;
and (3) that Iain and Norene looked for houses in
the United States.
  As we already have explained, the first finding funda-
mentally misreads the January 21 letter. There is no
need to repeat that discussion. Norene did not accept
the offer contained in the letter, and it therefore
dropped out of the picture.
  We have already pointed out the problem with the
second finding as well. Iain took prompt steps to secure
the children’s return by filing a request for return with
the Australian Central Authority in mid-February 2011,
as soon as it became apparent that a negotiated settle-
ment was not forthcoming.
  That leaves the third finding, which suggests that
the court may have concluded that Iain and Norene
came to the United States in June 2010 with the shared
intention of establishing a new habitual residence
in this country. Iain and Norene certainly could have
established a new habitual residence in this fashion. See,
e.g., id. at 715 (change in habitual residence accomplished
by a shared intent to abandon a prior habitual residence
plus an “actual change in geography”) (citing Mozes,
239 F.3d at 1078). But the district court never actually
said that they did so, and we cannot find enough in the
record to support the conclusion that Iain and Norene
16                                             No. 11-3602

arrived in the United States with the shared intention
of abandoning Australia and establishing a new habitual
residence here.
  In considering the parties’ intent, the district court
focused on Norene’s testimony that she and Iain looked
at real estate in San Francisco and Seattle when they
arrived in the United States in 2010. Norene testified
that she and Iain “talked extensively” about the housing
market, that she and a friend looked at a few houses in
San Francisco (while Iain remained in the car), and that
she and Iain met with a real estate agent in Seattle. Else-
where in its opinion, the district court also noted that
it was crediting Norene’s testimony that she and Iain
had always intended to return to the United States after
their 1998 move. The district court seemed to view this
intention to return as further evidence that the trip was
understood to be a permanent move, notwithstanding
the fact that Iain and Norene had been living in
Australia for 12 years by the time they came to the
United States in 2010.
  While parts of Norene’s testimony thus show that
the couple might have been considering relocating to
the United States, this is a perilously thin basis for
inferring that their trip in 2010 was truly intended to be
the start of that permanent move. Moreover, other
uncontroverted evidence undermines this inference.
For instance, the bulk of the family’s possessions, as well
as Chubba the family dog, remained in Australia; Iain
and Norene were in the process of rebuilding their
house in Australia; and Norene herself stated—both in
No. 11-3602                                             17

testimony and in emails to friends—that she intended
to stay in the United States until June 2011 at the latest,
and that she did not make up her mind to remain
in the United States until she received the January 21
letter. The evidence that Iain and Norene mutually in-
tended to abandon Australia and take up residence
in the United States is simply too contradictory and
underdeveloped to support the district court’s habitual
residence finding. Nor were the children in the United
States for so long prior to the filing of the petition for
return that their lives “bec[a]me so firmly embedded in
the new country as to make [them] habitually resident”
in the United States regardless of their parents’ lack of
mutual intent to establish a habitual residence here.
Mozes, 239 F.3d at 1078.


                            C
  Assuming that the children’s habitual residence
was Australia, Iain must still show he was “actually
exercis[ing]” his custody rights at the time of the reten-
tion. Art. 3. The standard for finding that a parent
was exercising his custody rights is a liberal one, and
courts will generally find exercise whenever “a parent
with de jure custody rights keeps, or seeks to keep, any
sort of regular contact with his or her child.” Bader v.
Kramer, 484 F.3d 666, 671 (4th Cir. 2007) (internal quota-
tion marks omitted). Indeed, “a person cannot fail to
‘exercise’ [his] custody rights under the Hague Conven-
tion short of acts that constitute clear and unequivocal
abandonment of the child.” Friedrich, 78 F.3d at 1066.
18                                            No. 11-3602

  As the Sixth Circuit has explained, sound policy
reasons support this liberal standard. U.S. courts are not
well equipped to determine whether the courts of a
child’s habitual residence would conclude that a parent
with de jure custody rights has nevertheless forfeited
those rights “because he or she was not acting suf-
ficiently like a custodial parent.” Id. at 1065. Moreover,
any determination that a parent has failed to behave
in a sufficiently parent-like fashion comes dangerously
close to an adjudication on the merits of the parents’
custody dispute, which (to repeat) is something the
Convention expressly reserves for the courts of the
child’s habitual residence. Id.; see also Arts. 1 & 19.
Finally, the “confusing dynamics” of domestic strife
“make it difficult to assess adequately the acts and mo-
tivations of a parent.” Friedrich, 78 F.3d at 1065.
  Although it acknowledged the liberal nature of the
standard, the district court nevertheless found that
Iain had “abandoned” his children. In support of this
rather extreme conclusion, the court noted that Iain did
not return to the United States after July 2010, that he
ceased supporting Norene financially after January 21,
2011, and that his January 21 letter was mainly con-
cerned with “the negotiation of support payments and
property settlement.”
  All of those things may be true, but they do not add up
to “unequivocal abandonment” of the children (as op-
posed, perhaps, to Norene). The district court overlooked
Norene’s undisputed testimony that Iain keeps “regular
contact” with the children by speaking to them weekly
No. 11-3602                                             19

over Skype. Further, in faulting Iain for failing to return
to the United States after July 2010, the district court
ignored Norene and Iain’s testimony that they had
always intended that Iain would return to Austra-
lia—both for work and to oversee the construction of
their house—in July or early August 2010. The court
also failed to mention that Norene testified that Iain
had plans to spend Christmas in the United States in
2010, and that he canceled those plans only after
Norene filed for divorce. Finally, just as the January 21
letter does not show that Iain consented to the children’s
remaining in the United States, it similarly does not
show that Iain was interested exclusively in reaching
a settlement regarding marital property. A letter that
requests custody for the children’s entire summer
vacation plus Christmas and asks for multiple visitation
opportunities at other times of the year can hardly be
characterized as indifferent to custody issues.
  This leaves Iain’s lack of financial support after
January 21, 2011, as the sole basis for finding abandon-
ment. This is not enough. Because non-exercise is evalu-
ated at the time of the retention—which, as we have
explained, must have occurred on January 21 or shortly
thereafter—Iain’s failure to provide support after the
retention is irrelevant to whether he was exercising
his custody rights when the wrongful retention began.
See, e.g., Baxter v. Baxter, 423 F.3d 363, 369 (3d Cir.
2005) (“[T]he record demonstrates that [the father]
‘actually exercised’ his custody rights under article 3 at
the time of the removal and retention.”); Mozes, 239 F.3d
at 1084-85 (“Nor is there any doubt that [the father]
20                                              No. 11-3602

was exercising his parental rights and responsibilities
up until the time [the mother] sought custody.”).
Neither the district court nor Norene identifies any case
in which a court has found abandonment based on a
lack of financial support, let alone a case that finds that
a parent may forfeit his rights under the Convention by
failing to send money to the abducting spouse even as
he works actively to have the children returned. Indeed,
the cases that address some version of this issue have
found that a parent does not fail to exercise his
custody rights merely by failing to provide financial
support for some period prior to the removal or reten-
tion. See Baxter, 423 F.3d at 369-70 (lack of financial sup-
port for several weeks prior to the retention did not
indicate that father was not exercising custody rights);
Habrzyk v. Habrzyk, 759 F. Supp. 2d 1014, 1023 (N.D. Ill.
2011) (infrequent financial support insufficient to show
non-exercise); In re Polson, 578 F. Supp. 2d 1064, 1072
(S.D. Ill. 2008) (father was exercising custody rights
even though he ceased to support family financially
after mother filed for divorce). Finally, we note that
whether one parent is required to pay support to the
other is an issue on the merits of a divorce proceeding,
and we are thus wary of allowing the presence or
absence of financial support to factor too prominently
in the analysis of the exercise of custody rights at the
time of the removal or retention.
  Using the appropriate standard, we cannot find on the
current record that Iain’s failure to provide financial
assistance while Convention proceedings are pending
amounts to a failure to exercise his custody rights.
No. 11-3602                                              21

                             D
   Finally, even if Iain had established a case for return
under the Convention, he could have waived that right
if he consented to, or acquiesced in, the children’s re-
maining in the United States with their mother. Art. 13.
Consent and acquiescence are analytically distinct
defenses to return under the Convention. Baxter, 423 F.3d
at 371. The consent exception applies when a petitioning
parent, either expressly or through his conduct, agrees
to a removal or retention before it takes place. Id. A par-
ent’s consent need not be formal, but “it is important
to consider what the petitioner actually contemplated
and agreed to in allowing the child to travel outside its
home country.” Id.; see also Mota v. Castillo, 692 F.3d 108,
117 (2d Cir. 2012); Larbie v. Larbie, 690 F.3d 295, 308-09
(5th Cir. 2012). Acquiescence is implicated if a peti-
tioning parent agrees to or accepts a removal or retention
after the fact. Baxter, 423 F.3d at 371. Unlike consent,
acquiescence must be formal, and might include “testi-
mony in a judicial proceeding; a convincing written
renunciation of rights; or a consistent attitude of acquies-
cence over a significant period of time.” Friedrich, 78
F.3d at 1070. One way or another, the “exceptions [must]
be drawn very narrowly lest their application under-
mine the express purposes of the Convention.” 51 Fed.
Reg. 10494, 10509 (Mar. 29, 1986). It is also worth remem-
bering that the Article 13 exceptions are permissive: a
court may order return even if it finds that the parent
opposing the petition has established that one of the
exceptions applies. Art. 13; 51 Fed. Reg. at 10509.
22                                               No. 11-3602

  The district court found that Norene had established
consent. The bases for this conclusion will by now be
familiar: they are the January 21 letter, which the
district court characterized as indicating Iain’s “uncon-
ditional consent” to the children remaining in the
United States, Iain’s failure to visit the United States
after July 2010, and his failure to provide financial support.
  Our concerns with the district court’s analysis will
also be familiar. The January 21 letter cannot be read as
an expression of consent, let alone unconditional con-
sent, to anything. The letter is an opening offer, a single
stage in a negotiation; it concedes nothing and in any
event was rendered null by the parties’ failure to come
to an agreement. It is apparent that Iain did not
“actually contemplate [or] agree” to the children’s re-
maining in the United States without Norene’s agree-
ment to conditions that she consistently rejected.
  Apart from the letter, the district court’s remaining
justifications are either clearly erroneous or irrelevant.
As previously discussed, Iain was involved in the chil-
dren’s lives after July 2010, and the discussion of fin-
ancial support is unrelated to Iain’s consent or acquies-
cence in the children’s remaining in the United States.


                             IV
  Having concluded that the district court’s decision in
this case cannot stand, we are left with the question of
how to proceed. Two options exist: an outright order
for the children to be returned to Australia pursuant to
No. 11-3602                                             23

the Convention, or a remand for further factfinding.
Although we regret the need to prolong this case
any further, we conclude that the latter is necessary.
Several crucial issues were not fully developed in the
previous proceedings, and these gaps in the record must
be filled before a final decision is rendered. On remand,
the district court must resolve at least the following
questions, taking evidence as necessary:
   1. What was Iain and Norene’s mutual intent re-
   garding the trip to the United States in June 2010?
   Was this intended as an extended vacation or as
   a permanent move?
   2. What has been the precise nature of Iain’s partici-
   pation in the Illinois divorce proceedings, and to
   what extent, if at all, does this participation indicate
   that Iain either consented to or acquiesced in the
   children’s retention in the United States?
   3. To the extent the children have “attained an
   age and degree of maturity at which it is appropriate
   to take account of their views,” Art. 13, what is the
   children’s attitude to being returned to Australia? In
   conducting this inquiry, we caution that the district
   court must be attentive to the possibility that the
   children’s views may be the product of “undue influ-
   ence” of the parent who currently has custody. 51
   Fed. Reg. 10510.


                            V
 In returning this case to the district court, we em-
phasize again that this is a dispute about which court
24                                          No. 11-3602

system should resolve the underlying issue of child
custody; it is not a dispute about which parent is
preferable or the terms under which custody will be
granted. We are confident that either the courts of
Western Australia or the courts of Illinois are fully
capable of resolving these matters. In that spirit, we
R EVERSE and R EMAND the judgment of the district court.




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