          United States Court of Appeals
                       For the First Circuit


No. 17-2036

                       NEREIDA RIVERA-COLÓN,

                       Plaintiff, Appellant,

                                 v.

    AT&T MOBILITY PUERTO RICO, INC.; ÁNGEL COUVERTIER-LÓPEZ;
                   CARLOS DELIZ; VICTOR PABÓN,

                       Defendants, Appellees,

              COMPANIES X, Y, Z; JANE DOES; JOHN DOES;
                    INSURANCE COMPANIES A, B, C,

                            Defendants.


          APPEAL FROM THE UNITED STATES DISTRICT COURT
                 FOR THE DISTRICT OF PUERTO RICO

         [Hon. Francisco A. Besosa, U.S. District Judge]


                               Before

                        Howard, Chief Judge,
              Torruella and Thompson, Circuit Judges.


     Rubén T. Nigaglioni, with whom Nigaglioni Law Offices P.S.C.
was on brief, for appellant.
     Kenneth W. Gage, with whom Sara B. Tomezsko, Paul Hastings
LLP, José F. Benítez-Mier, Iván Santos-Castaldo, and O'Neill &
Borges LLC were on brief, for appellees.
January 16, 2019
           THOMPSON,     Circuit      Judge.      Nereida    Rivera-Colón

("Rivera") filed suit against her former employer, AT&T Mobility

Puerto   Rico,   Inc.   ("AT&T"),1    alleging   age   discrimination   and

wrongful termination.       After AT&T pulled out its arbitration

agreement with Rivera, the district court sent the parties packing

to arbitrate.     Rivera now asks us to flip the district court's

order and allow her to slug it out with AT&T in court.           She says

that she shouldn't have to arbitrate her claims because she never

accepted AT&T's offer to arbitrate legal grievances in the first

place.   But because we conclude that she manifested her intent to

accept the agreement as per Puerto Rico law, we affirm.

                               BACKGROUND

           We start with a chronicle of the parties’ relationship

and how they ended up here, diving into some detail (for reasons

that will become apparent later).2




     1  She also sued some of her supervisors, who are the other
defendant-appellees, Ángel Couvertier-López, Carlos Deliz, and
Victor Pabón. But they raise the same arguments as AT&T, so we
just loop them in collectively with their employer, and call them
AT&T.
      2 Where, as here, the motion to compel arbitration was made

as part of a motion to dismiss or stay, "we glean the relevant
facts from the operative complaint and the documents submitted to
the district court in support of the motion."     Oliveira v. New
Prime, Inc., 857 F.3d 7, 9 n.1 (1st Cir. 2017), aff’d, ____ S. Ct.
____, No. 17-340, 2019 WL 189342 (U.S. Jan. 15, 2019).


                                     - 3 -
      A.   Rivera's Employment

            Their story begins in December 1997, when Rivera (then

in her late twenties) began her twenty years' tenure as an employee

of AT&T in Puerto Rico.       By 2006, she had worked her way up the

corporate ladder to become an Assistant Store Manager in AT&T's

retail location in Mayagüez, Puerto Rico.          There she supervised a

small team of employees who sold cell phones, service plans, and

all the like.     For the majority of her time with AT&T, she says

all went well.    She consistently received high performance ratings

and was praised by her superiors.

            But Rivera says everything changed beginning in 2015.

Out of the blue, she was transferred from her home base in Mayagüez

after twelve years there--even though she had seniority over the

other assistant manager, and even though transfers were supposed

to be based on seniority.         AT&T stationed her at another retail

location, this one a kiosk at the Aguadilla Mall, about an hour

drive from her home. She says this transfer was really a demotion.

The   Aguadilla    kiosk    had    lower   sales    (which   means   lower

commissions), worse hours, and less opportunity for promotion.

And, to boot, she says her supervision in Aguadilla was a far throw

away from congenial.       Now 49 years old, Rivera was supervised by

a manager fifteen years her junior who, according to her, placed

her on a performance improvement plan for no legitimate reason,

and harassed her because of her age.


                                   - 4 -
       B.     Rolling Out the Arbitration Agreement

               A few years before things turned sour, though, AT&T

rolled       out    an   arbitration   program      to   a   large    chunk   of    its

employees, including Rivera.3             On November 30, 2011, AT&T sent

Rivera an email (on her company email account with unique username

and password) informing her of the proposed change.                       The email

told Rivera that under the program, "employees and the company

would use independent, third-party arbitration rather than courts

or juries to resolve legal disputes."                    But unlike some other

arbitration programs, AT&T's wasn't mandatory.                    Instead, AT&T said

that       "[t]he    decision   on   whether   or    not     to   participate      [was

Rivera's] to make," and that if she didn't want to participate in

this alternative dispute resolution mechanism, she could opt out

by following two links:          one in the email, and one in the webpage

the email link opened.           There were no consequences for opting out

(except, of course, that Rivera couldn't force AT&T to arbitrate

its claims against her).

               The offer came with a proviso, though:              if Rivera didn't

opt out by the end of the day on February 6, 2012 (giving Rivera

sixty-eight days to respond), AT&T would take it as though she

opted in.          The email told her:    "[i]f you do not opt out by the




       3
       Before 2011, AT&T didn't have an independent arbitration
agreement with Rivera, or an arbitration provision in Rivera's
employment contract.


                                       - 5 -
deadline, you are agreeing to the arbitration process as set forth

in the Agreement.   This means that you and AT&T are giving up the

right to a court or jury trial on claims covered by the Agreement."

The email advised Rivera to review the agreement before making a

decision and instructed that if she wished to opt out, she needed

to open the agreement and "follow the link provided there to the

site where [she would] be able to electronically register [her]

decision to opt out."   AT&T sent the same email to Rivera twice

more--once in December 2011, and once in January 2012.   All three

emails included instructions on how to opt out.

           Opting out of the agreement required two steps.   First,

as the email said, Rivera would need to open the agreement and

acknowledge that she read it.     Every employee was required to

conduct this first step regardless of whether they chose to opt

out.    To complete this step, the employee needed to follow the

link provided in the email, which led to a webpage that contained

the full text of the agreement.   On that page, there was a button

marked "Review Completed" in the upper-left-hand corner of the

page.

           According to AT&T's records (and she doesn't contend

otherwise), Rivera completed this step and acknowledged that she

read the agreement.   Indeed, according to AT&T's internal records

of website traffic, Rivera viewed the arbitration agreement twice.

The first time was in December 2011, although she didn't click the


                               - 6 -
acknowledgement button then.             And on round two, she clicked the

acknowledgement button less than an hour after the January 17,

2012 follow-up email was sent.            Rivera doesn't dispute that it was

she who clicked "Review Completed," nor does she argue that she

clicked the acknowledgement button at the top of the page without

scrolling down to read the agreement.4

               Step two of the opt-out procedure:            the employee had to

click one additional link--this one in paragraph four of the

agreement on that webpage.          This paragraph, just a few lines into

the agreement, discussed the opportunity to opt out and laid out

the mechanism to do so:            "[i]f you choose to opt out, use this

link       . . .   which   will   take    you    to   the   site   where   you   can

electronically register your decision to opt out.                  That site will

generate and send you a written confirmation of your decision to

opt out."          And, according to AT&T, a cohort of thousands of

Rivera's colleagues followed that link and opted out of the

arbitration agreement.


       4
       The placement of the "Review Completed" button at the top
of the agreement makes it a type of "clickwrap" agreement where
the party doesn't need to actually scroll through the agreement
before accepting it. See Cullinane v. Uber Techs., Inc., 893 F.3d
53, 61 n.1 (1st Cir. 2018) (quoting Berkson v. Gogo LLC, 97
F. Supp. 3d 359, 394 (E.D.N.Y. 2015)) (discussing the different
types of acceptance processes for online agreements).           So,
technically, Rivera could have acknowledged the agreement without
ever scrolling through to read it in its entirety. But because
she doesn't argue that she never read the agreement, this case
isn't really about the new questions internet-based contracts like
these have raised, so we need not get into the weeds on that front.


                                         - 7 -
           Rivera has never argued, either to the district court or

to us, that she did follow that link and tried to opt out but that

the company just didn't register her decision.    Nor has she argued

that the opt-out procedure was confusing, or that she couldn't

find how to opt out.   In other words, she makes no argument that

she affirmatively chose to opt out--or even wanted to do so--at

the time the agreement was offered to her.

     C.   Their Litigation

           Eventually, AT&T fired Rivera in May 2016, and replaced

her with a 34-year-old.      Taking issue with the way things went

down, Rivera sued AT&T, her supervisors, and some other unnamed

parties (the last of which don't appear here) in the U.S. District

Court for the District of Puerto Rico.      She brought an array of

claims for violations of her civil rights, alleging that AT&T

discriminated against her for her age, in violation of Title VII

of the Civil Rights Act, 42 U.S.C. §§ 2000e, et seq.; Puerto Rico

Law 100, P.R. Laws Ann. tit. 29, §§ 146, et seq.; and Puerto Rico

Law 69, P.R. Laws Ann. tit. 29, §§ 1321, et seq.   She also alleged

wrongful termination under Puerto Rico Law 80, P.R. Laws Ann. tit.

29, §§ 185, et seq.

           Not so fast, said AT&T.   It entered a special appearance

and moved to stay the proceedings and compel arbitration, reminding

Rivera that she agreed to arbitrate these kinds of claims, not

bring them in court.   So AT&T asked the court to force Rivera to


                                - 8 -
go   to   arbitration,          thus    stripping    the     district       court     of

jurisdiction to hear the merits of the case.                       To support this

result, AT&T submitted hundreds of pages of affidavits and exhibits

to show that Rivera read the agreement and didn't opt out, and

therefore accepted it.

            Determined to stay where she was, Rivera opposed AT&T's

attempt to push her into arbitration, maintaining that there was

no valid arbitration agreement to begin with.                      She argued that

Puerto Rico law requires acceptance of a contract, and that her

mere failure to opt out can't meet the acceptance standard under

the Commonwealth's laws.

            Rejecting      Rivera's       contentions,       the    district       court

agreed    with     AT&T    and     said     the   arbitration        agreement       was

enforceable.       See Rivera-Colón v. AT&T Mobility P.R., Inc., 261

F. Supp. 3d 251, 256 (D.P.R. 2017).                 The judge looked to AT&T's

submitted evidence, which showed that Rivera received the emails

notifying    her    of     the     arbitration       agreement       and    that     she

acknowledged     that     she    read     the   agreement.         And,    given    that

evidence, the judge thought it clear that "AT&T gave [Rivera]

explicit notice that all disputes would be solved by arbitration"

so he granted AT&T's motion to compel arbitration and dismissed

Rivera's suit.5      See id. at 255-56.


     5  Although AT&T moved to stay the proceedings pending
arbitration of the claims, the district judge elected to dismiss


                                          - 9 -
             Clinging   to   the    assertions        she    advanced   below,     and

repeats here on appeal, Rivera says the district court got it all

wrong and asks us to reverse and give her the green light to

litigate her claims in court.

                                   DISCUSSION

     A.     Standard of Review

             Generally, we review an order compelling arbitration on

a spectrum of interwoven standards.                 At one end, when the appeal

raises    "solely    legal   issues       as   to    the    enforceability    of    an

arbitration clause," we look at it with a clean slate, or de novo.

Pelletier v. Yellow Transp., Inc., 549 F.3d 578, 580 (1st Cir.

2008); see also Britto v. Prospect Chartercare SJHSRI, LLC, 909

F.3d 506, 511 (1st Cir. 2018) (explaining de novo review in this

context).      The   same    de    novo    review      applies   when   the   facts

surrounding the agreement are undisputed and the only question is

whether they contractually bound themselves to arbitration on

those undisputed facts. See Cullinane v. Uber Techs., Inc., 893

F.3d 53, 60 (1st Cir. 2018).6             And given that the facts here are



the proceedings.    See, e.g., Next Step Med. Co. v. Johnson &
Johnson Int'l, 619 F.3d 67, 71 (1st Cir. 2010) (noting that, in
this circuit, a district court has discretion "to dismiss the law
suit, if all claims asserted in the case are found arbitrable").
The parties do not appeal this exercise of discretion.
     6 Although not applicable here, for the sake of thoroughness

we remind the careful reader that were the facts in dispute, we
would review the district court's determinations on a "sliding
scale." See Quint v. A.E. Staley Mfg. Co., 246 F.3d 11, 14 (1st
Cir. 2001). That is, "[t]he more the district court's conclusions


                                      - 10 -
undisputed the only question that remains is whether those facts

show that Rivera accepted the agreement as a matter of Puerto Rico

law.    So, we review that determination of the district court de

novo.       See Cullinane, 893 F.3d at 60.    That means we don't give

any deference to the district court's conclusion and look at the

legal issues with clear eyes.        See In re Extradition of Howard,

996 F.2d 1320, 1327 (1st Cir. 1993).         And it also means that we

"can affirm on any ground appearing in the record--including one

that the [district] judge did not rely on."       See Lang v. Wal-Mart

Stores E., L.P., 813 F.3d 447, 454 (1st Cir. 2016) (citing Collazo-

Rosado v. Univ. of P.R., 765 F.3d 86, 91 (1st Cir. 2014)).

              Bearing in mind this appellate lens, we return to the

legal issue before us.

       B.    A Primer on the Law

              For reasons that will become clear in the next section,

a legal primer will help frame our discussion.         So, we ask the

patient reader to bear with us as we lay it out.

              With the Federal Arbitration Act ("FAA"), Congress set

a "liberal federal policy favoring arbitration."         AT&T Mobility

LLC v. Concepcion, 563 U.S. 333, 346 (2011) (quoting Moses H. Cone

Memorial Hosp. v. Mercury Constr. Corp., 460 U.S. 1, 24 (1983)).



are characterized as factual conclusions, the more our review of
those facts is for clear error; the more the district court's
conclusions are conclusions of law, the more independent review we
give." Id.


                                   - 11 -
The FAA allows one party to an arbitration agreement to ask the

court to put the litigation on hold and force the other party to

arbitrate the disputes.    See 9 U.S.C. § 4.       At base, it respects

arbitration as "a matter of contract" between parties and doesn't

allow courts to jump in when the parties agreed to keep the courts

out of the mix.    See Henry Schein, Inc. v. Archer & White Sales,

Inc., ____ S. Ct. ____, No. 17-1272, 2019 WL 122164, at *3 (U.S.

Jan. 8, 2019).    It "places arbitration agreements on equal footing

with all other contracts," Buckeye Check Cashing, Inc. v. Cardegna,

546 U.S. 440, 443 (2006), which means that courts can invalidate

arbitration agreements only on the same "generally applicable

contract   defense[]"   grounds    that    would   apply   to   all   other

contracts, Doctor's Assocs., Inc. v. Casarotto, 517 U.S. 681, 687

(1996).

           But as a corollary to its contract-based philosophy, the

FAA's "liberal policy" is only triggered when the parties actually

agreed to arbitrate.     It "does not require parties to arbitrate

when they have not agreed to do so."         Volt Info. Scis., Inc. v.

Bd. of Trs. of Leland Stanford Jr. Univ., 489 U.S. 468, 478 (1989).

So, the existence of an enforceable agreement to arbitrate is the

first needed step to trigger the FAA's protective reach. See Nat'l

Fed'n of the Blind v. The Container Store, Inc., 904 F.3d 70, 80

(1st Cir. 2018) (noting that "a court should not compel arbitration

unless and until it determines that the parties entered into a


                                  - 12 -
validly formed and legally enforceable agreement covering the

underlying claims" (quoting Escobar-Noble v. Luxury Hotels Int'l

of P.R., Inc., 680 F.3d 118, 121 (1st Cir. 2012))).              And the party

seeking to compel arbitration (here, that's AT&T) bears the burden

of clearing that hurdle and "demonstrat[ing] that a valid agreement

to arbitrate exists."      Soto-Fonalledas v. Ritz-Carlton San Juan

Hotel Spa & Casino, 640 F.3d 471, 474 (1st Cir. 2011) (quoting

InterGen   N.V.   v.   Grina,   344   F.3d   134,   142   (1st    Cir.   2003))

(internal quotation marks omitted).

           Because     arbitration     is    a   creature    of     contract,

"principles of state contract law control the determination of

whether a valid agreement to arbitrate exists."                   Id. at 475

(quoting Campbell v. Gen. Dynamics Gov't Sys. Corp., 407 F.3d 546,

552 (1st Cir. 2005)).     Rivera and AT&T assume that Puerto Rico law

applies--a rational choice we won't disturb here given that Rivera

was employed in the Commonwealth.        See, e.g., Rodríguez v. United

States, 54 F.3d 41, 44 (1st Cir. 1995) (assuming that Puerto Rico

law applies when the parties assumed so and there was a "reasonable

relation" between the cause of action and Puerto Rico).              So, if an

enforceable contract exists under Puerto Rico law, we must enforce

that agreement "save upon such grounds as exist at law or in equity

for the revocation of any contract," 9 U.S.C. § 2, and send the

parties off to arbitrate.




                                  - 13 -
            This brings us to the skirmish the parties are waging

before us today.      Put simply:     if Rivera never agreed to arbitrate

her claims against AT&T, she's free to pursue them in court; but

if she did agree to arbitrate her claims against AT&T, she's bound

by   her   contract    and     she   must   resolve     those    claims    through

arbitration.     So, this is all we need to decide here.                  See Dean

Witter Reynolds, Inc. v. Byrd, 470 U.S. 213, 218 (1985) (noting

that the FAA "mandates that district courts shall direct the

parties    to   proceed   to    arbitration      on   issues    as   to   which   an

arbitration agreement has been signed"); see also Escobar-Noble,

680 F.3d at 122. The merits of her employment-based claims against

AT&T are left for another day, another umpire, and another ballpark

(whether judicial or arbitral).

      C.   The Arguments

            Against this backdrop, the parties argue primarily over

the application of Puerto Rico contract law.             Unsurprisingly, they

don't see eye to eye on how that law applies to the situation here.

            Rivera    argues     there's    no    enforceable        agreement    to

arbitrate because she never accepted AT&T's unsolicited offer.                    As

best we can tell, she makes this omnibus argument in what breaks

down into three waves.         First, according to her, Puerto Rico law

doesn't construe an offeree's silence or inaction as acceptance to

a contract offer when that offer was made at the offeror's sole

initiative.     She says that there was no bargaining between her and


                                      - 14 -
AT&T about the arbitration agreement, so she had no obligation to

respond to say yes or no to its offer.              And, she argues that under

Puerto Rico law, an offeror cannot impose on the offeree an

obligation to respond to an unsolicited offer.                 That is, if AT&T

makes an unsolicited offer, it can't force Rivera to respond and

say   no,    or    to   stipulate   that    her   lack   of   response    will    be

interpreted as saying yes.

              Wave two is a rebuttal point.          She says that even if she

could accept with her silence, the facts here don't unequivocally

show her intent to accept the contract, so she didn't accept this

agreement.        And in wave three, she adds two alternative arguments:

that this arbitration agreement is both a waiver of substantive

rights and a type of forum selection clause--both of which require

a heightened standard of acceptance under Puerto Rico law, which

can't be met here.

              AT&T, for its part, says that Puerto Rico law permits

silence as an avenue to acceptance of a contract, although it

acknowledges that there's no Puerto Rico precedent directly on

point.      But it says that under the limited precedent we have, the

facts of this case show that Rivera knew that her silence and

continued         employment   would       constitute    acceptance       of     the

arbitration        agreement--and    that     her    actions    show     that    she

willfully accepted.         It says that she acknowledged that she read

the provision that stipulated that her continued employment and


                                       - 15 -
failure   to   opt   out    of    the   agreement      would   constitute   her

acceptance.     And,   her       inaction    coupled    with   her   continued

employment shows that her conduct was informed and voluntary.               So,

Rivera demonstrated her will to accept AT&T's offer, and is bound

by the arbitration agreement.

                                   ANALYSIS

     A.   The Framework

           To assess these arguments, we first must look to the

framework of Puerto Rico contract law, and note some guideposts of

Puerto Rico law that shape our analysis.

           Puerto Rico is unique in many ways, its legal system

just one of them.          As a civil law jurisdiction, "Puerto Rico

eschews common law principles of contract interpretation in favor

of its own civil code derived from Spanish law."               Borschow Hosp.

& Med. Supplies v. Cesar Castillo Inc., 96 F.3d 10, 15 (1st Cir.

1996) (citing Guevara v. Dorsey Labs., Div. of Sandoz, Inc., 845

F.2d 364, 366 (1st Cir. 1988)).         So we can't use stateside common

law to "fill[] gaps in the civil law system" unless the Civil Code

and the Supreme Court of Puerto Rico are silent on the issue.

Guevara, 845 F.2d at 366 (citing Valle v. Am. Int'l Ins. Co., 108

D.P.R. 692, 696-97, 8 P.R. Offic. Trans. 735 (1979)).                 We turn

first to those sources.




                                    - 16 -
               To form a valid contract under Puerto Rico law, both

parties must consent to it.               See P.R. Laws Ann. tit. 31, § 3391.7

That       consent    "is    shown   by   the   concurrence     of   the   offer   and

acceptance of the thing and the cause which are to constitute the

contract."           P.R. Laws Ann. tit. 31, § 3401.              In simple terms:

"acceptance of an offer is . . . the normal procedure to perfect

a contract."          Producciones Tommy Muñiz Inc. v. Comité Organizador

de Los VIII Panamericanos (COPAN), 113 D.P.R. 517, 13 P.R. Offic.

Trans. 664, 670 (1982).               But "[c]onsent given by error, under

violence, by intimidation, or deceit shall be void."                       P.R. Laws

Ann. tit. 31, § 3404; see also Dialysis Access Ctr., LLC v. RMS

Lifeline, Inc., 638 F.3d 367, 378 (1st Cir. 2011) (discussing how

consent may be void under Puerto Rico law).

               This case presents a twist on the normal question,

though.        In the more typical case, the employee accepts the

contract by signing on the dotted line, thus leaving little doubt

that she accepted the agreement.                     But we consider here whether

Rivera       accepted       the   agreement     by    doing   nothing--through     her

inaction or silence.8




       7
       You also need to have "[a] definite object which may be the
subject of the contract," and "[t]he cause for the obligation which
may be established." P.R. Laws Ann. tit. 31, § 3391. But that's
not what the parties are arguing about here.
     8 We note that AT&T doesn't argue that Rivera accepted the

agreement when she acknowledged that she read it. It says that
she accepted it when she did not opt out and continued to work.


                                          - 17 -
          Although that brand of acceptance doesn't find its own

distinct provision in the Puerto Rican Civil Code, the Supreme

Court of Puerto Rico has recognized that not all acceptances are

in writing--implied consent to a contract is enough to meet the

Puerto Rico definition of acceptance.         See Teachers Annuity & Ret.

Sys. v. Sociedad de Gananciales, 115 D.P.R. 277, 15 P.R. Offic.

Trans. 372, 386-87 (1984); see also Colón Gutiérrez v. Registrador,

114 D.P.R. 850, 14 P.R. Offic. Trans. 1095, 1110 (1983) (noting

that   consent    to   an   agreement   can    be   given   "expressly   or

impliedly").     When it comes to this type of implied consent, "the

determining element . . . is the person's conduct and not the words

used to express such consent."      Teachers Annuity & Ret. Sys., 115

D.P.R. 277, 15 P.R. Offic. Trans. at 387.           That conduct "should

inequivocally [sic] show the will to consent," and the facts

"cannot be compatible with, another intent, or be subject to many

different interpretations."       Id. 115 D.P.R. 277, 15 P.R. Offic.

Trans. at 387-88.      And the party accepting must have "adequate

knowledge of the scope of [her] statement" to be able to adequately

evidence her consent.       See Colón Gutiérrez, 114 D.P.R. 850, 14

P.R. Offic. Trans. at 1111.        But on the precise question here

(whether silence is acceptance when the offeror conditions that it

will be), the Supreme Court of Puerto Rico has not spoken.

          When the Civil Code and the Supreme Court of Puerto Rico

are silent on an issue, we may forgo the traditional prohibition


                                  - 18 -
on use of common law principles and "employ the common law in its

multiple and rich versions . . . as a point of reference for

comparative law."        Valle, 108 D.P.R. 692, 8 P.R. Offic. Trans. at

738; see also Guevara, 845 F.2d at 366 (applying stateside common

law principles when "useful and persuasive" and when we "believe[d]

the Supreme Court of Puerto Rico would follow essentially the same

path"). That is particularly true when the Supreme Court of Puerto

Rico     has,   on   a    particular       subject,   "conformed   its   . . .

jurisprudence to common law principles."              Rodríguez, 54 F.3d at

45.      And in the contract-acceptance context, Puerto Rico law

"mimics the general law of contracts," Satellite Broad. Cable,

Inc. v. Telefónica de España, S.A., 807 F. Supp. 210, 216 (D.P.R.

1992), and operates in the same way as the "governing rule in the

United States," see COPAN, 113 D.P.R. 517, 13 P.R. Offic. Trans.

at 672 (referencing U.S. treatises Williston on Contracts and

Corbin on Contracts).           Which is all a long explanation of why we

will, at times, look to those stateside treatise sources to fill

in the gap here.

       B.   Addressing Those Arguments

             Wave I: Assessing Rivera's Intent in Silence

             With that legal outline in mind, we turn to the core of

this case:       do the (undisputed) facts unequivocally show that

Rivera      manifested    her     intent    to   accept   AT&T's   arbitration

agreement?


                                      - 19 -
             To tackle that question, we begin with a recount of one

of our prior cases, the closest we've gone to addressing an issue

like this under Puerto Rico law, which will prove instructive in

assessing the one before us now.        In Marrero-García v. Irizzary,

33 F.3d 117 (1st Cir. 1994), we discussed a similar, albeit

distinct, issue.     There, a utility company argued that residents

of a condominium complex impliedly accepted a contract to pay for

water services that the utility had already begun providing to

them.       See 33 F.3d at 122.      The utility company "repeatedly

requested the Condominium to place a bond and to register an

account," and informed the residents they needed to take these

actions to become "registered users."9       Id.    But when the residents

never posted a bond or registered with the utility company, the

utility company set up an account for them and started sending

bills for water.    The utility company then sued when the residents

refused to pay.       We rejected the utility company's implied-

acceptance     argument,   holding   that   the    residents'   refusal   to

register was not implied consent to the agreement to pay for water

services, but rather a rejection of that offer.                 And the key

takeaway we reap from this case is that "[a]n offeree's inaction

or 'silence in the face of the offer to sell goods is not ordinarily

an acceptance, because the offeror has no reason to believe from


        9
       The utility company didn't add a proviso deeming silence as
acceptance, like AT&T did here.


                                  - 20 -
the offeree's silence that the offeree promises to buy.'"        Id.

(quoting Farnsworth on Contracts § 3.15).

           To be sure, the facts of Rivera's case add a wrinkle to

a Marrero-García-style analysis:        AT&T specified that Rivera's

silence would constitute acceptance.      Rivera thinks this wrinkle

will cut in her direction.    She's correct that it makes all the

difference here, but it makes all the difference in a way she

doesn't imagine:   it is actually AT&T's stipulation of silence as

acceptance that tilts the scale away from Rivera's position, and

leads us to the opposite of the conclusion we reached in Marrero-

García.   Let us explain.

           Of course, as Rivera reminds us, it's basic contract law

that an offeror cannot unilaterally impose on another party the

obligation to respond and reject their offer.     See, e.g., 1 Corbin

on Contracts § 3.19 (2018) ("It should here be plainly set forth

that an offeror has no power to cause the silence of the offeree

to operate as an acceptance when the offeree does not intend it to

do so."); 2 Williston on Contracts § 6:50 (4th ed. 1993) ("Merely

sending an unsolicited offer does not impose upon the party

receiving it any duty to speak or deprive the party of its

privilege of remaining silent without accepting.").         But this

general statement of the law is just that--a generality.       There

are, as always, exceptions.   Indeed, the Restatement (which Rivera

cites in her brief) makes it clear that silence can operate as


                               - 21 -
acceptance "[w]here the offeror has stated or given the offeree

reason to understand that assent may be manifested by silence or

inaction, and the offeree in remaining silent and inactive intends

to   accept     the   offer."      Restatement   (Second)    of   Contracts

§ 69(1)(b); see also 2 Williston on Contracts § 6:53 ("If the

situation for any reason is such that a reasonable person would

construe silence as necessarily indicating assent, the offeree who

keeps silent, knowing that its silence will be misinterpreted,

should not be allowed to deny the natural interpretation of its

conduct.").      This aligns with the notion in Puerto Rico that

"silence could imply the tacit acceptance of an offer when,

pursuant   to    a    prior   relationship   between   the   parties,   the

responsibility arises for the one receiving the offer to take

affirmative action to reject it."            Danosa Caribbean, Inc. v.

Santiago Metal Mfg. Corp., 179 D.P.R. 40, No. CC-2008-882, slip

op. at 21 (2010) (Rodríguez Rodríguez, J., dissenting) (citing

Carlos Lasarte, 3 Principios del Derecho Civil 63 (4th ed. 1996)).10

           And that's where the scale flips away from Rivera.           AT&T

stipulated that if Rivera didn't opt out, it would take it as

though she opted in.            Rivera acknowledged that she read that

provision (both here in litigation, and when she acknowledged that




     10We requested that the parties file a certified translation
of this otherwise-untranslated case from the Supreme Court of
Puerto Rico.


                                    - 22 -
she read the agreement back in 2012).              It was laid out nose-to-

face plain and simple in the emails AT&T sent her, as well as in

the arbitration agreement that she confirmed she received and read.

So, by acknowledging that she read that proviso, she actually gave

AT&T "reason to believe from [her] silence that [she] promise[d]"

to arbitrate her claims, unlike the residents in Marrero-García.

See 33 F.3d at 122 (quoting Farnsworth on Contracts § 3.15). Thus,

these facts evidence Rivera's intent to accept the agreement.

               Wave II: Was That Intent Unequivocal?

               So we move on to wave two of her argument:       that even if

she could accept with her silence in these circumstances,11 the

facts here don't unequivocally show her intent to accept the

contract.

               Under Puerto Rico law, the facts "should inequivocally

[sic] show the will to consent . . . [and] cannot be compatible

with,        another   intent,   or     be    subject   to   many     different

interpretations."        Teachers Annuity & Ret. Sys., 115 D.P.R. 277,

15 P.R. Offic. Trans. at 387-88.             Rivera (quite obviously) argues

that her actions here don't unequivocally show her will to consent.

Her position is twofold.              First, she says that "there is no

scintilla of evidence on the record that [she] ever intended to

accept the offer.       In fact, the opposite holds true.           When [AT&T]


        11
       Indeed, Rivera acknowledges that silence can, "in certain
circumstances," constitute acceptance.


                                      - 23 -
attempted to enforce the 'contract,' [she] opposed."          And second

is that the facts only show that she "acknowledge[d] having

reviewed the document"; not that she intended to accept it.

Addressing these arguments in turn, they both fail.

            First, her objection to arbitration when this litigation

commenced in 2017 has no bearing on whether she manifested her

intent to accept the agreement back in 2012.        We say that for two

reasons:    one legal and one logical.     On the legal side, it doesn't

carry   weight   because   it   misses   the   operative   timeframe   for

assessing her intent.      It's basic Puerto Rico contract law that

contracts are formed and valid "from the moment" consent is given.

See P.R. Laws Ann. tit. 31, §§ 3371, 3375.          So, the question is

whether she manifested her intent to accept the agreement way back

in 2012 when she didn't opt out; not what happened in 2017.        Which

is all to say that this argument doesn't get her anywhere.             And

that's not to mention that the logical side of her argument is

baffling.     Disputes of this sort arise in litigation precisely

because a party later disputes whether they intended to accept a

contract.    So, if a party's later disavowment of their intent to

accept a contract bore any decisive weight (as Rivera seems to

suggest it should), it would make analysis unnecessary. This would

make the cases we just discussed pure excess--which they are not.

Cf. generally Teachers Annuity & Ret. Sys., 115 D.P.R. 277, 15

P.R. Offic. Trans. at 387-88 (looking to the facts at the time of


                                  - 24 -
the purported contract formation to determine if implied consent

existed even though the party later disputed their consent in

litigation); Cemex De P.R., Inc. v. Ductor, Inc., No. CIV.A. 09-

2254 (GAG), 2010 WL 1727834, at *1 (D.P.R. Apr. 26, 2010) (finding

that plaintiff sufficiently alleged implied consent even when the

party later disputed the consent during litigation).

             And her second argument (that her intent in clicking the

review completed button was to show only that she acknowledged

reading the agreement)12 is even more troubling and actually self-

defeating.     Again, it is critical to note that Rivera doesn't

attempt to say that she didn't know her silence would be treated

as opting in.     Instead of confronting this head on, though, her

argument tries to leapfrog over her contractual obligations by

relying on a general rule that AT&T couldn't make her respond.13


     12 In the same vein of this argument, Rivera also proposes a
new standard we should apply. She says that if AT&T wanted an
arbitration agreement with her, it should have made it so that she
"would have taken affirmative steps to clearly and unmistakenly
[sic] affirm her intent to be bound by an agreement to arbitrate."
But imposing that requirement would force us to ignore the Supreme
Court of Puerto Rico's clear instruction that a contract can be
formed with implied consent.    See generally Teachers Annuity &
Ret. Sys., 115 D.P.R. 277, 15 P.R. Offic. Trans. 372.       And we
cannot do so. See, e.g., Wainwright v. Goode, 464 U.S. 78, 84
(1983) ("[T]he views of the state's highest court with respect to
state law are binding on the federal courts."); Rochester Lincoln-
Mercury, Inc. v. Ford Motor Co., 248 F.3d 46, 48 (1st Cir. 2001)
(same).
     13 To support this argument, Rivera provides us with one- or

two-sentence excerpts from three Spanish commentators about
silence as a mode of acceptance under the Spanish Civil Code.
Initially, the translations were made only by her counsel, which


                                - 25 -
But this argument strikes out just as quickly as the first, because

it glances over the exception (rooted in notions of good faith)

that aims to root out the type of maneuvers she's trying to make

here:   "the offeree who keeps silent, knowing that [her] silence

will be misinterpreted, should not be allowed to deny the natural

interpretation of [her] conduct." 2 Williston on Contracts § 6:53.

          That exception is especially pertinent in situations

like this (just as the Restatement, Corbin, and Williston have

noted14), where "given a certain relationship between two people,

the current way of proceeding implies the duty to speak."   Danosa




was out of compliance with our Local Rule requiring certified
translations of Spanish documents. See 1st Cir. Local R. 30.0(e).
In her reply brief, Rivera provided certified translations of those
three snippets, but not the broader context from which they came.
And, as we've said in the past, isolated excerpts from treatises
not translated into English are not useful support. See, e.g.,
United States v. Ramos-González, 775 F.3d 483, 505 & n.26 (1st
Cir. 2015) (noting that a counsel-translated sentence from a
Spanish-language treatise on Puerto Rico's penal code, not
otherwise available in English, is not "useful support" for an
argument). Especially given the potential for these excerpts to
be read out of context, we decline to use them here.
     14 See Restatement (Second) of Contracts § 69(1)(c) (noting

the exception where silence is acceptance "because of previous
dealings or otherwise, it is reasonable that the offeree should
notify the offeror if he does not intend to accept"); 1 Corbin on
Contracts § 3.18 ("Often, however, silence coupled with conduct or
with expectations engendered by a prior relationship can
reasonably be understood by the offeror as an acceptance."); 2
Williston on Contracts § 6:50 (noting that "the relationship
between the parties or other circumstances surrounding the
transaction may be such as to justify the offeror in expecting a
reply, and, therefore, in assuming that silence in fact does
indicate assent to its proposal").


                              - 26 -
Caribbean, 179 D.P.R. 40, slip op. at 21 (Rodríguez Rodríguez, J.,

dissenting) (quoting Lasarte, 3 Principios del Derecho Civil 63).

                Unlike the unsolicited offer-by-mail to which Rivera

tries to liken this case, this wasn't an offer made by a stranger.

Rivera and AT&T were engaged in a long-standing, close legal

relationship as employee and employer.                 That relationship--one in

which        AT&T   and    its    employees   regularly     communicated   company

business        with      one    another    via     email15--implicates    Rivera's

knowledge that she had the duty to speak and that her choice not

to would be reasonably interpreted by AT&T as acceptance.                      Cf.

Circuit City Stores, Inc. v. Najd, 294 F.3d 1104, 1109 (9th Cir.

2002) (O'Scannlain, J.) (noting in a very similar context under

California law that the employee and employer "were not two typical

parties contracting at arm's length," and that the employee had a

responsibility to affirmatively opt out if he didn't want to

accept).        And when "the one who can and should speak does not do

so, it must be deemed that [s]he consents for the sake of good

faith . . . because in such cases, it is natural and normal to

manifest dissent."              Danosa Caribbean, 179 D.P.R. 40, slip op. at

21 (Rodríguez Rodríguez, J., dissenting) (emphasis added) (quoting

Lasarte, 3 Principios del Derecho Civil 63).                      So absent her

dissent, the natural interpretation of her conduct is that she


        15
       AT&T communicated at least twenty corporate policies to its
employees in the year prior to the arbitration proposal.


                                           - 27 -
accepted.     And that must stand.   Thus, we agree with the district

court that Rivera impliedly accepted this arbitration agreement

and is bound by it.

             Wave III: A Heightened Standard of Acceptance

             But wait, Rivera has two alternative arguments to try to

steer us back to her side.    She calls this agreement both a waiver

of substantive rights and a forum selection clause.          And she

contends that under Puerto Rico law, this means that a heightened

standard of acceptance should apply to the agreement.        That is,

standard modes of consent aren't enough to accept this type of

agreement.     But unfortunately for Rivera, these arguments don't

move the needle in her direction.

             First, she argues that a heightened standard of contract

acceptance should apply here because the agreement is a waiver of

a substantive right (the substantive right being her right to a

jury trial).    And, under Puerto Rico law, "such renunciation[s] of

rights . . . must be clear, conclusive, express, and unequivocal."

Quiñones Quiñones v. Quiñones Irizarry, 91 D.P.R. 225, 91 P.R.R.

217, 257 (1964).

             But even assuming she waived a substantive right with

this agreement--and a jury trial is decidedly a procedural right,

see, e.g., Libretti v. United States, 516 U.S. 29, 53-54 (1995)

(Souter, J., concurring) (recognizing the right to a jury trial is

a procedural right)--her argument smacks up against one of the


                                - 28 -
core principles of the FAA:         a state (or territory) cannot apply

any standard to an arbitration agreement that it does not apply to

contracts in general, see Soto v. State Indus. Prods., Inc., 642

F.3d 67, 74 (1st Cir. 2011) ("[W]hile Puerto Rico may impose

special restrictions on noncompetition agreements, it is preempted

from imposing special restrictions on arbitration agreements.");

see also Doctor's Assocs., Inc., 517 U.S. at 687 (noting that with

the FAA, "Congress precluded States from singling out arbitration

provisions     for   suspect    status,    requiring   instead   that   such

provisions be placed 'upon the same footing as other contracts'").

             And that Supreme Court command also torpedoes her second

argument     that    this   supposed      "forum   selection"    agreement16

manifesting as an arbitration agreement can be void for public

policy.    She says that in Puerto Rico, forum selection agreements

are unenforceable if:          "(1) they were not freely negotiated or

were the result of overweening bargaining power; or (2) they

contravene a strong public policy."          But again, even assuming for

the sake of argument that Rivera can meet one of these grounds,

under the FAA's protective grasp, an arbitration agreement can be

voided only on "generally applicable contract defense[]" grounds

that would apply to all other contracts.           Doctor's Assocs., Inc.,




     16 By this, we mean an agreement between parties specifying
where they'll duke out their legal disputes. See, e.g., Marra v.
Papandreou, 216 F.3d 1119, 1123 (D.C. Cir. 2000).


                                    - 29 -
517 U.S. at 687. And although Puerto Rico can hold forum selection

clauses to a higher standard, it "is preempted from imposing

special restrictions on arbitration agreements."           See Soto, 642

F.3d at 74.     So her final argument falls flat.

      C.   Postscript

              Before we sum up, we add one last point.       The careful

reader will notice that we reach our ultimate conclusion on the

key   issue    here   (whether   Rivera    impliedly   consented   to   the

arbitration agreement) under a different legal standard than the

district court.17     And on that subject, we add a postscript.

              The district court judge said the focal point of the

legal question was "whether AT&T gave [Rivera] explicit notice

that all disputes would be solved by arbitration."         Rivera-Colón,

261 F. Supp. 3d at 256 (citing García-Clara v. AIG Ins. Co. P.R.,

No. CV 15-1784CCC, 2016 WL 1261058 (D.P.R. 2016)).         That test, in

our view, misses the point.      The contract formation question here

is whether Rivera accepted the contract--not whether she was merely

on notice of the contract's existence.

              The district court (and the García-Clara court on which

it relied) seems to have misconstrued our holdings in Campbell v.

General Dynamics Government Systems Corp., 407 F.3d 546 (1st Cir.


      17Again, we're free to take this different route under de
novo review because we're free to "affirm on any ground appearing
in the record--including one that the [district court] judge did
not rely on." Lang, 813 F.3d at 454.


                                  - 30 -
2005), and Rosenberg v. Merrill Lynch, Pierce, Fenner & Smith,

Inc., 170 F.3d 1 (1st Cir. 1999).            In those cases, the question

was, in fact, one of notice.       They turned on whether the employer

gave the employees sufficient notice that certain statutory claims

(those   under   the   Americans   with     Disabilities   Act,   42   U.S.C.

§§ 12101, et seq.) would be covered under an arbitration agreement.

And that was so important because the ADA has a specific provision

that limits arbitration of claims to situations when it would be

"appropriate."     See 42 U.S.C. § 12212.        So that was relevant to

the arbitrability of the particular claims at issue there, not the

arbitrability of all claims under the sun.          But here, the parties

don't dispute that the particular claims are arbitrable.           The only

question is whether a valid arbitration agreement existed in the

first place, which means that the question is one of contract

acceptance--not notice.     See Campbell, 407 F.3d at 554 (explaining

that the questions of whether there was a valid arbitration

agreement and whether the parties had notice that ADA claims were

covered under it were "independent, yet overlapping, issues").

                                   WRAP-UP

           Our work done, and finding, as we do, that the district

court got the outcome right, we affirm the order compelling

arbitration.     Costs to appellees.      See Fed. R. App. P. 39(a)(2).




                                   - 31 -
