United States Court of Appeals

For the First Circuit

No. 20-1997

JOHN WATERS,

individually and for others similarly situated,

Plaintiff, Appellee,

v.

DAY & ZIMMERMANN NPS, INC.

Defendant, Appellant.

APPEAL FROM THE UNITED STATES DISTRICT COURT

FOR THE DISTRICT OF MASSACHUSETTS

[Hon. Nathaniel M. Gorton, U.S. District Judge]

Before

Thompson, Dyk,* and Barron,

Circuit Judges.

David B. Salmons, with whom Michael J. Puma, James D. Nelson, 

and Morgan, Lewis & Bockius LLP were on brief, for appellant.

Richard J. (Rex) Burch, with whom Michael A. Josephson, 

Richard M. Schreiber, Taylor A. Jones, Bruckner Burch PLLC, and 

Josephson Dunlap LLP were on brief, for appellee.

Daryl Joseffer, Jonathan D. Urick, Nicole A. Saharsky, Andrew 

J. Pincus, Archis A. Parasharami, Minh Nguyen-Dang, and Mayer Brown 

LLP on brief for Chamber of Commerce of the United States of 

America, amicus curiae.

* Of the United States Court of Appeals for the Federal 

Circuit, sitting by designation. 
January 13, 2022
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DYK, Circuit Judge. John Waters filed suit for overtime 

wages pursuant to § 216(b) of the Fair Labor Standards Act 

("FLSA"), 29 U.S.C. §§ 201–219, in the United States District Court 

for the District of Massachusetts. The defendant was Day & 

Zimmermann ("D&Z"), a company incorporated in Delaware that 

maintains its principal place of business in Pennsylvania.

Waters's suit alleged that D&Z failed to pay him and 

other similarly situated employees and former employees their 

FLSA-required overtime wages. In accord with the FLSA's procedures 

governing what are often referred to as "collective actions," more 

than 100 current and former D&Z employees from around the country 

filed "opt-in" consent forms with the district court electing to 

participate as plaintiffs in Waters' suit. 

D&Z moved to dismiss for lack of personal jurisdiction. 

This motion was based on Bristol-Myers Squibb v. Superior Court of 

California ("BMS"), 137 S. Ct. 1773, 1779, 1781 (2017), holding 

that in view of the Fourteenth Amendment, state courts cannot 

entertain a state-law mass action—an aggregation of individual 

actions—if it includes out-of-state plaintiffs with no connection 

to the forum state. Here, the claims subject to the motion to 

dismiss were the claims of the current and former D&Z employees 

who had opted in to the collective action but, who, unlike Waters, 

had worked for the company outside of Massachusetts.

Notwithstanding that D&Z had been properly served with process, it
- 4 -

claimed that under BMS, these claims could not be brought in a 

Massachusetts federal court, even though a federal court's 

jurisdiction is determined by the Fifth Amendment Due Process 

Clause. This is so, D&Z argued, because Federal Rule of Civil 

Procedure ("FRCP" or "Rule") 4(k)(1) independently limits a 

federal court's exercise of personal jurisdiction with respect to 

out-of-state opt-in claimants added after service of process has 

been effectuated. The district court denied D&Z's motion,

declining to extend BMS's personal jurisdiction requirements to 

FLSA cases in federal court. Waters v. Day & Zimmermann NPS, Inc., 

464 F. Supp. 3d 455, 461 (D. Mass. 2020). 

On this interlocutory appeal, we now affirm the district 

court's denial of D&Z's motion.1

I.

The following facts are not in dispute. Waters formerly 

worked for D&Z in Plymouth, Massachusetts. He served as a 

mechanical supervisor for the company, which provides services to 

power plants.

On July 22, 2019, Waters filed an FLSA-based "collective 

action" complaint against D&Z. That complaint alleged that D&Z 

violated the FLSA's overtime-wage provisions, see § 207(a)(1), 

because it "paid Waters and other workers like him the same hourly 

1 We acknowledge with appreciation the assistance of the 

amicus curiae in this case.
- 5 -

rate for all hours worked, including those in excess of 40 in a 

workweek." Waters sought unpaid overtime wages as liquidated 

damages, and attorneys' fees on behalf of himself and "the Putative 

Class Members."

About two weeks later, on August 8, 2019, Waters served

the complaint on D&Z pursuant to 4(c) of the FRCP, utilizing the 

provisions of Massachusetts' long-arm statute. Mass. Gen. Laws 

ch. 223A, § 3. The following month, others claiming to be current

or former D&Z employees filed written "opt-in" consent forms

pursuant to § 216(b) in the district court to participate in the 

collective action that Waters had filed.

The standard opt-in consent form contained the following 

language:

1. I hereby consent to participate in a 

collective action lawsuit against Day & 

Zimmermann to pursue my claims of unpaid 

overtime during the time that I worked with 

the company.

2. I understand that this lawsuit is brought 

under the Fair Labor Standards Act, and 

consent to be bound by the Court's decision. 

3. I designate the law firm and attorneys at 

JOSEPHSON DUNLAP and BRUCKNER BURCH as my 

attorneys to prosecute my wage claims. 

4. I authorize the law firm and attorneys at 

JOSEPHSON DUNLAP and BRUCKNER BURCH to use 

this consent to file my claim in a separate 

lawsuit, class/collective action, or 

arbitration against the company.
- 6 -

To date, over 100 opt-ins claiming to be current and former D&Z 

employees have filed consent forms electing to participate in the 

FLSA collective action that Waters filed. 

On September 12, 2019, D&Z moved pursuant to FRCP 

12(b)(2) to dismiss the claims of those opt-ins who had not been 

employed by D&Z in Massachusetts. D&Z explained that, in so 

moving, it did not seek to "challenge personal jurisdiction as to 

the named Plaintiff's [i.e., Waters's] individual claim, as he 

allege[d] that he previously worked for [D&Z] in Massachusetts."

Nor did D&Z contend that it had not properly been served with 

process or that anyone other than the named plaintiff was required 

to serve D&Z with process. Instead, D&Z's motion and accompanying 

memorandum of law claimed that BMS required the dismissal of the 

opt-in claims because the district court lacked either general or 

specific personal jurisdiction as to those claims.

In BMS, the Supreme Court held that the Fourteenth 

Amendment's Due Process Clause prevented a California state court 

from exercising specific personal jurisdiction over nonresident 

plaintiffs' state-law claims when those claims had no connection 

to the forum state. 137 S. Ct. at 1781. The decision expressly 

reserved the separate question "whether the Fifth Amendment 

imposes the same restrictions on the exercise of personal 

jurisdiction by a federal court." Id. at 1784. 
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On June 2, 2020, the district court here denied D&Z's 

motion to dismiss the opt-in claims based on BMS. It determined 

that the Supreme Court's ruling in that case had no bearing on its 

exercise of personal jurisdiction over the opt-ins because 

Waters's suit was brought in federal court pursuant to the FLSA's 

provisions governing collective actions, and the opt-ins had 

joined his suit in accord with that statute's procedures for doing 

so. Waters, 464 F. Supp. 3d at 461. In reaching this decision, 

the district court noted that BMS was "specifically limited to 

'the due process limits on the exercise of specific jurisdiction 

by a State'" and did not resolve "whether the Fifth Amendment 

imposes the same restrictions" on a federal court. Id. (quoting 

BMS, 137 S. Ct. at 1783–84).

Following the denial, D&Z moved in the district court 

for a certificate of appealability under 28 U.S.C. § 1292(b), 

which the district court granted, see Waters v. Day & Zimmermann 

NPS, Inc., No. 19-cv-11585-NMG, 2020 WL 4754984, at *1 (D. Mass. 

Aug. 14, 2020). This court granted D&Z's timely petition for 

permission to bring an interlocutory appeal on October 14, 2020.2 

We have appellate jurisdiction under 28 U.S.C. § 1292(b).

2 The district court has stayed the proceedings below pending 

our resolution of D&Z's interlocutory appeal.
- 8 -

II.

Before addressing the merits of D&Z's appeal, we first 

consider an issue that neither party raises, but that could affect 

our appellate jurisdiction: whether the opt-in plaintiffs were

parties to the action in the district court. If the dismissed 

opt-in plaintiffs were not parties to the action, we may lack 

jurisdiction to consider the propriety of their dismissal. See 

Campbell v. City of Los Angeles, 903 F.3d 1090, 1105 (9th Cir. 

2018) ("All 'those that properly become parties[] may appeal an 

adverse judgment.'" (quoting Marino v. Ortiz, 484 U.S. 301, 304 

(1988))). The opt-ins' party status hinges on the question whether 

they become parties as a result of filing opt-in notices, or they 

could become parties only after the district court conditionally 

certified that they were "similarly situated."

The FLSA provides that employees serving as named 

plaintiffs can bring collective actions on "behalf of . . .

themselves and other employees similarly situated." § 216(b). 

The FLSA does not provide for conditional certification, but in 

the "absence of statutory or case law guidance," district courts

at or around the pleading stage have developed a "loose consensus"

regarding conditional certification procedures. Campbell, 903 

F.3d at 1108–09. This process entails a "lenient" review of the 

pleadings, declarations, or other limited evidence, id. at 1109

(citation omitted), to assess whether the "proposed members of a 
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collective are similar enough to receive notice of the pending 

action," Swales v. KLLM Transp. Servs., L.L.C., 985 F.3d 430, 436

(5th Cir. 2021). 

Conditional certification has no bearing on whether the 

opt-in plaintiffs become parties to the action. The FLSA provides 

that "[n]o employee shall be a party plaintiff to any such action 

unless he gives his consent in writing to become such a party and 

such consent is filed in the court in which such action is 

brought." § 216(b). This provision makes clear that in collective 

actions, opt-in plaintiffs become parties to the proceedings when 

they give "consent in writing to become such a party and such 

consent is filed in the court."3 Id. 

Conditional certification cannot be the cornerstone of 

party status because it is not a statutory requirement; rather, 

certification "is a product of interstitial judicial lawmaking or 

3 The relevant portion of subsection (b) reads as 

follows, in part: 

An action to recover the liability prescribed 

in the preceding sentences may be maintained 

against any employer (including a public 

agency) in any Federal or State court of 

competent jurisdiction by any one or more 

employees for and in behalf of himself or 

themselves and other employees similarly 

situated. No employee shall be a party 

plaintiff to any such action unless he gives 

his consent in writing to become such a party 

and such consent is filed in the court in which 

such action is brought.
- 10 -

ad hoc district court discretion . . . nothing in section 216(b) 

expressly compels it." Campbell, 903 F.3d at 1100; see also Myers

v. Hertz Corp., 624 F.3d 537, 555 n.10 (2d Cir. 2010) ("Thus 

'certification' is neither necessary nor sufficient for the 

existence of a representative action under [the] FLSA, but may be 

a useful 'case management' tool for district courts to employ in 

'appropriate cases.'" (quoting Hoffmann-La Roche Inc. v. Sperling, 

493 U.S. 165, 169, 174 (1989))). 

Both the Supreme Court and nearly all of our sister 

circuits that have considered the question agree that opt-in 

plaintiffs become parties to the action without regard to 

conditional certification. Genesis Healthcare Corp. v. Symczyk,

569 U.S. 66, 75 (2013), concerned the justiciability of an FLSA

collective action when the named plaintiff's claims became moot

and no opt-in plaintiffs had joined in the action prior to that 

occurring. See Symczyk v. Genesis Healthcare Corp., 656 F.3d 189, 

197 (3d Cir. 2011) (noting that "no other potential plaintiff ha[d] 

opted in to the suit"). The Supreme Court rejected the idea that 

the action was not moot because it could be remanded to 

conditionally certify the collective, since "'conditional 

certification' does not produce a class with an independent legal 

status, or join additional parties to the action. The sole 

consequence of conditional certification is the sending of courtapproved written notice to employees . . . who in turn become 
- 11 -

parties to a collective action only by filing written consent with 

the court." Genesis Healthcare, 569 U.S. at 75 (first citing 

Hoffmann-La Roche, 493 U.S. at 171-72; then citing § 216(b)).

Almost all circuits to address this issue interpret the 

statute as making opt-in plaintiffs parties to the action as soon 

as they file consent forms. See, e.g., Campbell, 903 F.3d at 1104

("The FLSA leaves no doubt that 'every plaintiff who opts in to a 

collective action has party status.'" (quoting Halle v. W. Penn 

Allegheny Health Sys. Inc., 842 F.3d 215, 225 (3d Cir. 2016))); 

Mickles v. Country Club Inc., 887 F.3d 1270, 1278 (11th Cir. 2018) 

("The plain language of § 216(b) supports that those who opt in 

become party plaintiffs upon the filing of a consent and that 

nothing further, including conditional certification, is 

required."); Simmons v. United Mortg. and Loan Inv., LLC, 634 F.3d 

754, 758 (4th Cir. 2011) ("[I]n a collective action under the FLSA, 

a named plaintiff represents only himself until a similarlysituated employee opts in as a 'party plaintiff' by giving 'his 

consent in writing to become such a party and such consent is filed 

in the court in which such action is brought.'" (quoting § 216(b)); 

Anson v. Univ. of Tex. Health Sci. Ctr. at Hous., 962 F.2d 539, 

540 (5th Cir. 1992) ("Under Section 216(b), an employee may become 

an 'opt-in' party plaintiff to an already filed suit by filing 

written consent with the court where the suit is pending."). D&Z 

also agrees that once an opt-in plaintiff "file[s] their consent 
- 12 -

with the court, [they] have full party status." Appellant's Br. 

26 (emphasis in original); see also id. at 2. 

The sole possible exception to the general recognition 

that opt-in plaintiffs become parties to the action upon filing 

consent forms is the Seventh Circuit's decision in Hollins v. 

Regency Corp., 867 F.3d 830, 833 (7th Cir. 2017), which held that 

appellate review of a named plaintiff's adverse summary judgment 

decision was not precluded by the presence of other parties when

"the collective action has never been conditionally certified and 

the court has not in any other way accepted efforts by the unnamed 

members to opt in or intervene." The decision attributed 

significance to the district court's failure to conditionally 

certify the collective action, or to "accept[] efforts by the 

unnamed members to opt in or intervene." Id. at 833–34. There is 

no indication that the Hollins court would find lack of party 

status in a case like this, in which the opt-in forms were accepted

as filed by the district court. 

Although Canaday v. Anthem Cos., 9 F.4th 392 (6th Cir. 

2021), and Vallone v. CJS Solutions Group, 9 F.4th 861 (8th Cir. 

2021), reached a different ultimate result on the question of 

personal jurisdiction, both support our view that the dismissed 

opt-in plaintiffs were parties to the action. In Canaday and 

Vallone, the Sixth and Eighth Circuits faced the same BMS-based 

personal jurisdiction challenge that D&Z raises now. In those 
- 13 -

cases, opt-in plaintiffs had joined the action by filing consent 

forms. Both district courts resolved the defendants' personal 

jurisdiction challenges and dismissed the out-of-state opt-in

claims before reaching the merits of the in-state plaintiffs'

requests for conditional certification, signifying that it was not 

necessary to decide the certification issue first. See Canaday v. 

Anthem Cos., 439 F. Supp. 3d 1042, 1049 (W.D. Tenn. 2020); Vallone

v. CJS Sols. Grp., 437 F. Supp. 3d 687, 691 (D. Minn. 2020). The 

Sixth Circuit explicitly agreed that the nonresident opt-in 

plaintiffs became parties regardless of conditional certification, 

stating that "[o]nce they file a written consent, opt-in plaintiffs 

enjoy party status as if they had initiated the action," Canaday, 

9 F.4th at 394, and "once they opt in, these plaintiffs become 

'party plaintiff[s]' . . . enjoying 'the same status in relation 

to the claims of the lawsuit as do the named plaintiffs,'" id. at 

402–03 (first quoting § 216(b); then quoting Prickett v. DeKalb 

County, 349 F.3d 1294, 1297 (11th Cir. 2003)).4

We note that collective actions are distinct from FRCP 

23 class actions in that the latter's putative class members do 

not become parties until after certification, see Smith v. Bayer 

Corp., 564 U.S. 299, 315 (2011), and putative class members who 

have not intervened in an action cannot appeal denials of class 

4 The Eighth Circuit did not appear to address this question 

but did not disagree with the district court's approach.
- 14 -

certification, Deposit Guaranty Nat'l Bank v. Roper, 445 U.S. 326, 

330, 332 n.5 (1980) (citing United Airlines, Inc. v. McDonald, 432 

U.S. 385 (1977)); see also Molock v. Whole Foods Mkt. Grp., Inc., 

952 F.3d 293, 298 (D.C. Cir. 2020) ("Putative class members become 

parties to an action—and thus subject to dismissal—only after class 

certification."). These Rule 23 class action cases have no bearing 

on whether the opt-in plaintiffs here became parties to the action. 

In short, the FLSA's text, Supreme Court precedent, and 

a majority of circuit court decisions compel only one conclusion: 

the opt-ins who filed consent forms with the court became parties 

to the suit upon filing those forms. Nothing else is required to 

make them parties. Because more than 100 current and former D&Z 

employees filed consent waivers in the district court, there are 

that many opt-in party-plaintiffs before this court. We proceed 

to decide whether the district court properly denied D&Z's motion 

to dismiss the nonresident opt-in claims for lack of personal 

jurisdiction. 

III. 

D&Z argues that BMS requires our dismissal of the 

nonresident opt-in claims because the Massachusetts district court

lacked either general or specific personal jurisdiction as to those 

claims. A detailed description of BMS provides helpful context. 

In BMS, a group of nearly 700 plaintiffs filed eight separate 

complaints in California state court alleging state-law products 
- 15 -

liability, negligent misrepresentation, and misleading advertising 

claims. 137 S. Ct. at 1778. The plaintiffs' purported injuries

all stemmed from Plavix, a drug manufactured and sold by BMS. Id. 

Pursuant to a California procedural rule that permitted post-hoc 

consolidation of the eight separate complaints, the plaintiffs 

combined their suits into one mass-tort action.5 See BristolMyers Squibb Co. v. Superior Court of California, 175 Cal. Rptr.

3d 412, 416 (Ct. App. 2014). The combined suit consisted of a 

majority of non-resident plaintiffs, none of whom obtained Plavix

in California, used the drug there, or received treatment for their

injuries there. Id. BMS did, however, sell 187 million Plavix 

pills in California, and it earned more than $900 million from 

those sales. Id. 

Citing these "extensive contacts with California" and 

the similarity of the resident and nonresident claims, the 

California Supreme Court held that the state could properly

exercise specific jurisdiction over the mass-action. Id. at 1779.

Rejecting this conclusion, the U.S. Supreme Court held that the 

Fourteenth Amendment's Due Process Clause prohibits state courts 

from exercising specific personal jurisdiction over state-law 

claims asserted by nonresident plaintiffs absent a "connection 

5 In California, "coordination" allows complex civil actions 

that are "pending in different courts," but that share "a common 

question of fact or law" to be consolidated in one proceeding. 

Cal. Civ. Proc. § 404.
- 16 -

between the [state] forum and the specific claims at issue." Id.

at 1781, 1783. Similarities between the nonresident claims and 

the claims of residents or those who were injured in California 

were insufficient to establish that connection. Id. at 1781. 

The decision emphasized that the "burden on [a] 

defendant"—the "primary concern" animating jurisdictional 

restrictions—encompasses more than just the "practical problems 

resulting from litigating in the forum." Id. at 1780. These 

restrictions also protect defendants from "submitting to the 

coercive power of a State that may have little legitimate interest 

in the claims in question," a "federalism interest" that is "at 

times . . . decisive." Id. The Supreme Court explained:

[E]ven if the defendant would suffer minimal 

or no inconvenience from being forced to 

litigate before the tribunals of another 

State; even if the forum State has a strong 

interest in applying its law to the 

controversy; even if the forum State is the 

most convenient location for litigation, the 

Due Process Clause, acting as an instrument of 

interstate federalism, may sometimes act to 

divest the State of its power to render a valid 

judgment.

Id. at 1780-81 (quoting World-Wide Volkswagen Corp. v. Woodson, 

444 U.S. 286, 294 (1980)). 

The Court's reasoning in BMS rests on Fourteenth 

Amendment constitutional limits on state courts exercising 

jurisdiction over state-law claims. Here, it is agreed that the

Fourteenth Amendment does not directly limit a federal court's 
- 17 -

jurisdiction over purely federal-law claims. Rather, as a 

constitutional matter, the "constitutional limits" of a federal 

court's jurisdiction over federal-law claims "are drawn in the 

first instance with reference to the [D]ue [P]rocess [C]lause of 

the [F]ifth [A]mendment," a point which D&Z concedes, as it must. 

See Lorelei Corp. v. County of Guadalupe, 940 F.2d 717, 719 (1st 

Cir. 1991). The Fifth Amendment does not bar an out-of-state 

plaintiff from suing to enforce their rights under a federal 

statute in federal court if the defendant maintained the "requisite 

'minimum contacts' with the United States."6 See United Elec., 

Radio & Mach. Workers of Am. v. 163 Pleasant St. Corp., 960 F.2d 

1080, 1085 (1st Cir. 1992). There is no contention here that the 

opt-in plaintiffs lack such contacts with the United States; that 

the Fifth or Fourteenth Amendments themselves bar suit by the nonresident opt-in plaintiffs; or that BMS directly governs a suit in 

federal court under a federal statute, such as this one. Nor is 

there any contention that D&Z was not properly served with process 

pursuant to FRCP 4(c) and the Massachusetts long-arm statute. 

Nonetheless, D&Z claims that the Fifth Amendment is 

"wholly irrelevant" to the personal jurisdiction question before 

6 "Because the United States is a distinct sovereign, a 

defendant may in principle be subject to the jurisdiction of the 

courts of the United States but not of any particular State." J. 

McIntyre Mach., Ltd. v. Nicastro, 564 U.S. 873, 884 (2011) 

(plurality opinion).
- 18 -

us—notwithstanding that this is a federal question case being heard 

in federal court—because Rule 4(k) "incorporates the Fourteenth 

Amendment's limits on the jurisdiction of federal courts wherever 

a federal statute does not provide for nationwide service of 

process." In other words, they propose that Rule 4 is not 

concerned merely with service of process, but with personal 

jurisdiction generally. Thus, D&Z argues, because there is no 

dispute that the FLSA does not authorize nationwide service of 

process, Rule 4(k) independently makes the holding of BMS

applicable to the FLSA opt-ins. 

This argument depends on the contention that Rule 

4(k)(1) governs not just service of a summons, but also limits a 

federal court's jurisdiction after the summons is properly served. 

We must decide whether D&Z is right that Rule 4(k)(1) operates as 

a free-standing limitation on the exercise of personal 

jurisdiction in collective actions such as those enabled by the 

FLSA. We do not find D&Z's contention persuasive, as we now 

discuss.

IV.

The question before us is one of rule interpretation. 

As such, our review is de novo. See Sam M. ex rel. Elliott v. 

Carcieri, 608 F.3d 77, 86 (1st Cir. 2010) (citing NEPSK, Inc. v. 

Town of Houlton, 283 F.3d 1, 5 (1st Cir. 2002)). 
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A.

We start with the relevant text. The text reveals that 

Rule 4 is limited to setting forth various requirements for 

effectively serving a summons on a defendant in federal court, 

thereby establishing personal jurisdiction over the defendant. 

BNSF Ry. Co. v. Tyrrell, 137 S. Ct. 1549, 1556 (2017) ("[A] basis 

for service of a summons on the defendant is prerequisite to the 

exercise of personal jurisdiction." (citing Omni Cap. Int'l, Ltd.

v. Rudolf Wolff & Co., 484 U.S. 97, 104 (1987)); see also Walden

v. Fiore, 571 U.S. 277, 283 (2014) ("[A] federal district court's 

authority to assert personal jurisdiction in most cases is linked 

to service of process on a defendant."); Canaday, 9 F.4th at 395 

("Over time, service of process became a prerequisite for obtaining 

authority over a defendant, making it appropriate to say that 

'service of process conferred jurisdiction.'" (quoting Burnham v. 

Superior Ct. of Cal., 495 U.S. 604, 613 (1990))). 

Indeed, Rule 4's title, "Summons," suggests that it is 

concerned only with service. The notes accompanying the 

committee's 1993 amendment to Rule 4 reveal that the title was 

changed from "Process" to "Summons" to show that the rule's 

requirements "applie[d] only to that form of legal process." 

Amendments to Fed. R. Civ. P. 4, 146 F.R.D. 401, 559 (1993). 

Turning to subsection (k) of Rule 4, it is apparent that

it addresses an aspect of how a summons may be served. Like the 
- 20 -

rule as a whole, it, too, bears a title that adverts to the 

requirements for effecting service of a summons: "Territorial 

Limits of Effective Service." Specifically, paragraph (1) of 

subsection (k) limits the instances in which "[s]erving a summons

or filing a waiver of service establishes personal jurisdiction 

over a defendant":

(k) Territorial Limits of Effective Service.

(1) In General. Serving a summons or 

filing a waiver of service establishes 

personal jurisdiction over a defendant: 

(A) who is subject to the 

jurisdiction of a court of general 

jurisdiction in the state where the 

district court is located;

(B) who is a party joined under Rule 

14 or 19 and is served within a 

judicial district of the United 

States and not more than 100 miles 

from where the summons was issued; 

or

(C) when authorized by federal 

statute.

Fed. R. Civ. P. 4(k)(1)(A)–(C) (emphasis added). Thus, while the

text states that personal jurisdiction can be "establishe[d]" by

"[s]erving a summons" so long as any of these three criteria is

met, it nowhere suggests that Rule 4 deals with anything other

than service of a summons, or that Rule 4 constrains a federal

court's power to act once a summons has been properly served, and

personal jurisdiction has been established.

We see no textual basis in Rule 4 for concluding that

the district court's exercise of jurisdiction over the opt-in
- 21 -

claims would be improper when "there is no dispute the named 

plaintiff properly served [D&Z]" by serving a summons in accord 

with Rule 4(c); D&Z does not contend that such service failed to 

satisfy the territorial limits of Rule 4(k)(1)(A) given that Waters 

had been employed by D&Z in Massachusetts; see United Electric, 

960 F.2d at 1087 (citing Mass. Gen. Laws ch. 223A, § 3), and D&Z

conceded that the opt-ins are not "responsible" for serving a

summons.7 

To be sure, Rule 4(k)(1)(A) does make the due process 

standard of the Fourteenth Amendment applicable to federalquestion claims in federal court when a plaintiff relies on a state 

long-arm statute for service of the summons. Rule 4(k)(1)(A) 

requires looking to state law to determine whether service is 

effective to confer jurisdiction, and "because state law is subject 

to Fourteenth Amendment limitations, the minimum contacts 

doctrine, while imposing no direct state-by-state constraint on a 

federal court in a federal question case, acts indirectly as a 

governing mechanism for the exercise of personal jurisdiction." 

United Electric, 960 F.2d at 1086. But this is not the same thing 

as saying that Rule 4 or the Fourteenth Amendment governs district 

7 The Sixth Circuit in Canaday agreed that the opt-ins have

no service obligations under Rule 4. 9 F.4th at 399–400 ("After

Anthem appeared in the case in response to Canaday's service of

the complaint, it is true, the nonresident plaintiffs . . . had no

additional service obligation under Civil Rule 4(k).").
- 22 -

court jurisdiction in federal question cases after a summons has 

been properly served; had it been the FRCP drafters' intention to 

have Rule 4 govern more than the service of a summons, they could 

have simply said that additional plaintiffs may be added to an 

action if they could have served a summons on a defendant 

consistent with Rule 4(k)(1)(A). But that was not the choice the 

drafters made, and for good reason. It would be anomalous to apply 

the Fourteenth Amendment, rather than the Fifth Amendment, to 

federal causes of action after a summons is properly served.8

Significantly, FRCP 82 also states that "[t]hese rules do not

extend or limit the jurisdiction of the district courts." Fed. R.

Civ. P. 82; see also Miss. Publ'g Corp. v. Murphree, 326 U.S. 438,

445 (1946) ("Rule [4(k)(1)(A)] serves only to implement the

jurisdiction . . . Congress has conferred, by providing a procedure

by which the defendant may be brought into court at the place where

Congress has declared that the suit may be maintained.")

8 The dissent cites various law review articles suggesting 

changes to Rule 4(k) that would expand the jurisdiction of federal 

courts. See Scott Dodson, Personal Jurisdiction and Aggregation, 

113 NW. U. L. REV. 1, 37-40 (2018); see also Stephen E. Sachs, How 

Congress Should Fix Personal Jurisdiction, 108 NW. U. L. REV. 1301, 

1316 (2014); A. Benjamin Spencer, The Territorial Reach of Federal 

Courts, 71 FLA. L. REV. 979, 990-91 (2019). With one exception, 

see infra note 12, none of the articles discusses the particular 

issue addressed here: whether Rule 4(k) continues to apply after 

service of process has been effectuated.
- 23 -

B.

Apart from the text of Rule 4(k), its history shows that 

its limited purpose was to govern service of a summons, not to 

limit the jurisdiction of the federal courts after a summons has 

been served. The first version of Rule 4(f), (now Rule 4(k))

entitled "Territorial Limits of Effective Service," required that 

for process to be effectively served, it must be physically served

"anywhere within the territorial limits of the state in which the 

district court is held" unless a federal statute authorized service 

"beyond the territorial limits of that state." Fed. R. Civ. P. 

4(f) (1937). This geographical limit prevented a plaintiff from 

serving a defendant anywhere outside of the state in which the 

underlying lawsuit would take place, consistent with the thengeographically-based concept of "tag" jurisdiction. See Pennoyer

v. Neff, 95 U.S. 714, 733 (1878). 

Due to the "changes in the technology of transportation 

and communication, and the tremendous growth of interstate 

business activity," business operations transcended the bounds of 

any one state, rendering jurisdiction based on physical presence 

largely obsolete. Daimler AG v. Bauman, 571 U.S. 117, 126 (2014) 

(quoting Burnham, 495 U.S. at 617). Responding to this change, 

International Shoe Co. v. Washington, 326 U.S. 310, 316 (1945)

(quoting Milliken v. Meyer, 221 U.S. 457, 463 (1940)), eliminated

the physical presence requirement, holding that Fourteenth 
- 24 -

Amendment due process is satisfied for jurisdictional purposes 

when a defendant has "certain minimum contacts [with the forum] 

such that the maintenance of the suit does not offend 'traditional 

notions of fair play and substantial justice.'" 

The 1963 version of Rule 4(f), also entitled 

"Territorial Limits of Effective Service," reflected the

principles set forth in International Shoe. Citing "[a]n important 

and growing class of State [long-arm] statutes [that] base personal 

jurisdiction over nonresidents on the doing of acts or on other 

contacts within the State," Rule 4 was amended to "expressly 

allow[] resort in original Federal actions to the procedures 

provided by State law for effecting service on nonresident 

parties." Amendments to Fed. R. Civ. P. 4, 31 F.R.D. 587, 627-28

(1963). Specifically, Rule 4(f) was "amended to assure the 

effectiveness of service outside the territorial limits of the 

State" when allowed by state law. Id. at 629 (emphasis added).

The amended text allowed process to be served "anywhere within the 

territorial limits of the state in which the district court is 

held, and, when authorized by a statute of the United States or by 

these rules, beyond the territorial limits of that state." Id. at 

594.

Later amendments to other provisions of Rule 4 also show

that the rule evolved to simplify service, not to govern 

jurisdiction after service. The 1980 amendments expanded the 
- 25 -

category of individuals who could act as process servers from 

marshals, deputies, and individuals specifically appointed by the 

court to include any person "authorized to serve process in an 

action brought in the courts of general jurisdiction of the state 

in which the district court is held or in which service is made." 

Amendments to Fed. R. Civ. P. 4, 85 F.R.D. 521, 524 (1980). Despite 

this expansion, the 1983 amendments recognized that the job of 

serving process still largely fell on marshals in states that did 

not authorize additional process servers, and they also reflected 

views that mail service and other methods of service prescribed by 

state law were of paramount importance. Amendments to Fed. R. 

Civ. P. 4, 96 F.R.D. 81, 118-19 (1983). The 1983 amendments

overhauled Rule 4(c) (now Rule 4(c), (e)) to allow a summons to 

"be served by any person who is not a party and is not less than 

18 years of age" and permitted service "by mailing a copy of the 

summons . . . to the person to be served." Id. at 82–83. In

response to efforts to "delete[] the provision" authorizing 

service pursuant to the law of the forum state, the 1983 amendments 

"saw no reason to forego systems of service that had been 

successful in achieving effective notice," and incorporated that 

provision into the new version of Rule 4(c). Id. at 83, 119. 

The final amendment to Rule 4(k) occurred in 1993. 

Subdivision (f) became subdivision (k), and the committee notes

emphasized that the amendment's purpose was to "facilitate the 
- 26 -

service of the summons and complaint" and to "explicitly 

authorize[] a means for service of the summons and complaint on 

any defendant." 146 F.R.D. at 558. The amended rule "retain[ed] 

the substance of the former rule" by "explicitly authorizing the 

exercise of personal jurisdiction over persons who can be reached 

under state long-arm law." Id. at 570. 

The fact that 4(k)(1)(A) provides that "service of a 

summons" establishes personal jurisdiction over defendants by 

utilizing a given state's long-arm statute incorporating 

Fourteenth Amendment requirements does not show that the 

Fourteenth Amendment applies to federal-law claims after service 

is satisfied. See 4 Charles A. Wright, Arthur R. Miller & Adam N.

Steinman, Federal Practice and Procedure § 1007 (4th ed. 2021)

("The rule was also amended to clarify when service of a summons

would establish personal jurisdiction in federal court."). In 

fact, the advisory committee notes make clear that a federal

court's jurisdiction once service has been effectuated is

determined by the Fifth Amendment's Due Process Clause at least in

federal actions. 146 F.R.D. at 566 ("Service of the summons under

this subdivision does not conclusively establish the jurisdiction

of the court over the person of the defendant. A defendant may

assert the territorial limits of the court's reach set forth in

subdivision (k), [i.e. whether the service is effective under state

or federal law to confer jurisdiction] including the
- 27 -

constitutional limitations that may be imposed by the Due Process

Clause of the Fifth Amendment."). Thus, although serving a summons

in accordance with state or federal law is necessary to establish

jurisdiction over a defendant in the first instance, the Fifth

Amendment's constitutional limitations limit the authority of the

court after service has been effectuated at least in federal-law

actions. 

C.

Another reason that we cannot read Rule 4(k)(1)(A) as 

limiting the court's authority over the added plaintiffs is that 

FRCP 20 already defines that authority. Rule 20 sets the limit 

for allowing additional parties to join a pre-existing lawsuit, 

permitting joinder of those parties with claims arising out of the 

"same transaction [or] occurrence" and presenting common 

"question[s] of law or fact." Fed. R. Civ. P. 20(a)(1)(A), (B). 

The FLSA's "similarly situated" limitation for collective actions

displaces Rule 20 and limits the range of individuals who may be 

added as opt-in plaintiffs by requiring that they be "similarly 

situated." See, e.g., Cruz v. Bristol-Myers Squibb Co., PR, 699 

F.3d 563, 569 (1st Cir. 2012) (The similarly situated "requirement 

is even less stringent than the test for party joinder" (citations 

omitted)); Campbell, 903 F.3d at 1104–05 ("The natural parallel is 

to plaintiffs . . . later added under the ordinary rules of party 

joinder."); Chamber of Comm. Br. 12 ("[T]he FLSA's opt-in provision 
- 28 -

is properly viewed as a rule of joinder." (citation omitted)). We 

are not aware of, and D&Z has not cited, a case in which a court 

held that Rule 4 applies to plaintiffs joined under Rule 20.

Finally, the FLSA and its legislative history show that 

Congress created the collective action mechanism to enable all 

affected employees working for a single employer to bring suit in 

a single, collective action. The FLSA's purpose was to allow

efficient enforcement of wage and hour laws against large, multistate employers, a "broad remedial goal" that the Supreme Court 

has instructed "should be enforced to the full extent of its 

terms." Hoffman-La Roche, 493 U.S. at 173.

The FLSA's original premise was to target those

employers engaged in interstate commerce, defined as "trade,

commerce, transportation, transmission, or communication among the

several States or from any State to any place outside thereof." 

Fair Labor Standards Act of 1938, ch. 676, § 3(b), 52 Stat. 1060. 

Specifically, the legislative history evinces congressional intent

to "provide a living wage" for workers at large, multi-state

businesses, such as Sears Roebuck, General Motors, and Coca-Cola. 

82 Cong. Rec. 1815–16 (1937) (remarks of Rep. Adolph Sabath); see

also 93 Cong. Rec. 2182 (1947) (remarks of Sen. Donnell)

(contemplating a suit in which "John Smith files a suit on behalf

of himself and all other employees of the United States Steel

Corporation" (emphasis added)). The congressional debates also
- 29 -

reveal a clear intent for a collective action to allow a "suit by

one or more employees, for himself and all other employees

similarly situated," regardless of the state in which they were

employed. Id. (emphasis added). 

Interpreting the FLSA to bar collective actions by outof-state employees would frustrate a collective action's two key 

purposes: "(1) enforcement (by preventing violations and letting 

employees pool resources when seeking relief); and (2) efficiency 

(by resolving common issues in a single action)." Swales, 985 

F.3d at 435 (citing Bigger v. Facebook, 947 F.3d 1043, 1049 (7th 

Cir. 2020)); see also Hoffman-La Roche, 493 U.S. at 170 ("A 

collective action allows . . . plaintiffs the advantage of lower 

individual costs to vindicate rights by the pooling of resources. 

The judicial system benefits by efficient resolution in one 

proceeding of common issues of law and fact arising from the same 

alleged discriminatory activity.").

Holding that a district court lacks jurisdiction over

the non-resident opt-in claims would "force[] those plaintiffs to

file separate lawsuits in separate jurisdictions against the same

employer based on the same or similar alleged violations of the

FLSA." Canaday, 9 F.4th at 415–16 (Donald, J., dissenting). That

is not what the FLSA contemplated. 
- 30 -

V.

As we have noted earlier, the Sixth and Eighth Circuits, 

faced with BMS-based personal jurisdiction challenges to FLSA 

collective actions, disagree with the decision that we reach today. 

Neither decision suggests that the Fourteenth Amendment directly 

limits federal-court authority to entertain multi-state collective 

actions. Both opinions instead rely on an erroneous reading of 

Rule 4, and fail to successfully confront the fact that Rule 4(k) 

is a "territorial limit" on "effective service" of a summons, and 

thus logically cannot be read to limit a federal court's 

jurisdiction after a summons is properly served.

In this respect, the Eighth Circuit, with little 

discussion, reached the same result as the Sixth Circuit, ruling 

it "a given" that the Fourteenth Amendment, by way of Rule 4,

limited the court's jurisdiction with respect to all of the claims, 

including those of the opt-in plaintiffs. Vallone, 9 F.4th at 

865. The Sixth Circuit opinion is more expansive.9 It concluded

that even for "amended complaints and opt-in notices, the district 

court remains constrained by . . . the host State's [] personal 

jurisdiction limitations." Canaday, 9 F.4th at 400 (citing Tamburo

v. Dworkin, 601 F.3d 693, 700–01 (7th Cir. 2010)). But Tamburo,

the only case cited in support of this proposition, is silent on 

9 The Sixth Circuit's decision was an interlocutory appeal 

pursuant to 28 U.S.C. § 1292(b). See Canaday, 9 F.4th at 395.
- 31 -

whether Rule 4 concerns the scope of personal jurisdiction after 

service of a summons. The case involved only a single, original 

plaintiff and the original defendants. The sole plaintiff served

a summons under Rule 4 and the state's long-arm statute. See 601 

F.3d at 698, 700. Since the personal jurisdiction issue in Tamburo

concerned only the original plaintiff's state-law claims, id. at 

700–01, the court had no occasion to consider its jurisdiction 

over federal claims or parties added after a summons was properly 

served.10

The other authorities relied on by the Sixth Circuit do 

not come close to addressing whether 4(k) and the Fourteenth 

Amendment apply to federal-law claims after a summons has been 

properly served pursuant to a state long-arm statute.11 See Handley

v. Ind. & Mich. Elec. Co., 732 F.2d 1265, 1269 (6th Cir. 1984)

(affirming district court's exercise of jurisdiction over 

nonresident defendant served by original plaintiff pursuant to 

10 The Seventh Circuit affirmed the district court's 12(b)(6) 

dismissal of the federal-law claims before addressing personal 

jurisdiction over the state-law claims. Tamburo, 601 F.3d at 699–

700. 

11 The dissent here also cites Old Republic Insurance Co. v. 

Continental Motors, Inc., 877 F.3d 895, 902-03 (10th Cir. 2017), 

for the proposition that a "plaintiff's amended complaint is 'the 

operative one' for the purpose of analyzing" a defendant's motion 

to dismiss for lack of personal jurisdiction. Old Republic is 

similar to Tamburo, as it also involved neither federal claims nor 

the application of Rule 4 to parties added after service of process 

had been effectuated. 
- 32 -

Rule 4); SEC v. Ross, 504 F.3d 1130, 1138-40 (9th Cir. 2007)

(holding that a court lacked jurisdiction over a defendant who was 

never served with or named as a party in the federal-law complaint, 

despite statute's nationwide service of process provision).12 

The Sixth Circuit opinion rests on a supposed anomaly

resulting from our interpretation—that added parties and added

claims are not subject to Rule 4's limitations. The Sixth Circuit

warned that reading Rule 4(k)(1)(A) as applying only to plaintiffs

responsible for serving a summons risks "limitations on judicial 

power [being] one amended complaint—with potentially new claims 

and new plaintiffs—away from obsolescence." Canaday, 9 F.4th at 

400; see also Molock, 952 F.3d at 309 (Silberman, J., dissenting)

(suggesting that Rule 4(k) must be interpreted broadly to ensure

that "litigants [cannot] easily sidestep the territorial limits on 

personal jurisdiction simply by adding claims—or by adding 

plaintiffs, for that matter—after complying with Rule 4(k)(1)(A) 

in their first filing").

12 The opinion also relied on an article that states "courts 

regularly apply Rule 4(k)(1)(A) limitations to the claims 

appearing in amended complaints," but this proposition is also 

supported only by Tamburo. See A. Benjamin Spencer, Out of the 

Quandary: Personal Jurisdiction Over Absent Class Member Claims 

Explained, 39 REV. LITIG. 31, 43–44 (2019). Another statement cited 

in Canaday, see 9 F.4th at 400, that "Rule 4(k) remain[s] the 

operative constraint[] that district courts apply to . . . new 

claims by newly joined parties," cites the same article, which 

cites no support, see 39 REV. LITIG. at 44. 
- 33 -

There is no anomaly. As discussed above, Rule 4 is 

concerned with initial service, not jurisdictional limitations 

after service. And the consequence is not that additional parties 

and claims can be added to escape jurisdictional limitations. In 

both the case of added parties and claims, the court's jurisdiction 

is still subject to constitutional limitations—in the case of 

federal-law claims, the Fifth Amendment—and statutory limitations

governing subject matter jurisdiction and venue. See 7 Charles A.

Wright, Arthur R. Miller & Adam N. Steinman, Federal Practice and

Procedure § 1659 (3d ed.) ("[T]he statutory jurisdiction and venue

requirements are fully applicable to Federal Rule of Civil

Procedure 20 and may restrict the ability to join parties.")13 If 

there is any anomaly, it is the approach suggested by the Sixth 

Circuit—applying the Fourteenth Amendment to federal-law claims 

that are governed only by the Fifth Amendment. 

The Sixth Circuit also relied on the FLSA's failure to

authorize nationwide service of process, urging that because the 

FLSA lacks a nationwide service of process provision, that left 

Rule 4(k)(1)(A) as the only basis for establishing jurisdiction. 

See Canaday, 9 F.4th at 396. We agree that "a basis for service 

13 Also, claims "radically different from those set out in the 

original pleading," may require courts to "direct personal service 

of the new pleading on the [defendant] pursuant to Rule 4." 4B

Charles A. Wright, Arthur R. Miller & Adam N. Steinman, Federal

Practice and Procedure § 1146 (4th ed.).
- 34 -

of a summons on the defendant is prerequisite to the exercise of 

personal jurisdiction," BNSF, 137 S. Ct. at 1556 (citing Omni 

Capital, 484 U.S. at 104), and 4(k)(1)(A) is the sole basis for 

service when nationwide service is not authorized. But the absence 

of a nationwide-service provision in the FLSA only requires resort 

to state law for service of process. See United States v. Swiss 

Am. Bank, Ltd., 274 F.3d 610, 618 (1st Cir. 2001) ("[I]n federal 

question cases . . . a plaintiff need only show that the defendant 

has adequate contacts with the United States as a whole . . . 

[H]owever, the plaintiff must still ground its service of process 

in a federal statute or civil rule.") It says nothing about 

whether 4(k)(1)(A) constrains the court's jurisdiction once 

service is effectuated.14

Finally, much of the Sixth Circuit opinion sought to 

distinguish FLSA collective actions and Rule 23 class actions, 

likening collective actions to the mass action in BMS. See

Canaday, 9 F.4th at 402–03. We agree that FLSA collective actions 

and Rule 23 class actions are dissimilar in myriad ways. The 

paramount similarity, and the only one that matters for purposes 

14 The Sixth Circuit contended that such an interpretation 

would render nationwide service of process provisions pointless. 

Canaday, 9 F.4th at 399 ("What indeed would be the point of these 

provisions if Civil Rule 4(k) already allowed jurisdiction and 

service?"). But our interpretation of Rule 4(k) does not allow 

nationwide service in all cases. Initial service must still rely 

on state law when there is no nationwide service provision.
- 35 -

of assessing the district court's jurisdiction here, is that the 

named plaintiff in both actions is the only party responsible for 

serving the summons, and thus the only party subject to Rule 4.15 

VI.

Accordingly, we affirm the district court's denial of 

D&Z's motion to dismiss the nonresident opt-in plaintiffs. The 

decision is

Affirmed. Costs to appellee. 

-Dissenting Opinion Follows15 A separate Sixth Circuit opinion recently held that the 

personal jurisdiction inquiry in a Rule 23 class action is required 

only for a named plaintiff's claims because "a class action is 

formally one suit in which, as a practical matter, a defendant 

litigates against only the class representative," and "absent 

class members are not considered 'parties,' as a class 

representative is, for certain jurisdictional purposes." See

Lyngaas v. Curaden AG, 992 F.3d 412, 435 (6th Cir. 2021). 
- 36 -

BARRON, Circuit Judge, dissenting. The majority today 

decides a significant question of first impression in our Circuit 

about the meaning of Federal Rule of Civil Procedure 4(k)(1)(A). 

It does so in a manner that creates a direct conflict with the 

ruling of two circuits and that will have seemingly wide-ranging 

effects on a slew of cases that have nothing to do with the specific 

dispute at hand. In my view, there is no reason for us to decide 

this question at this time, given the interlocutory posture of 

this appeal. Thus, I write separately to explain why, for reasons 

independent of the merits of the majority's ruling, I dissent.

I.

Federal Rule of Civil Procedure 4(k)(1)(A) provides that 

a summons "establishes" personal jurisdiction over a defendant in 

a civil action that is brought in federal court if the defendant 

"is subject to the jurisdiction of a [state] court of general 

jurisdiction in the state where" the civil action commenced. In 

response to relatively recent developments in the law that defines 

the limits that the Fourteenth Amendment's Due Process Clause 

places on the exercise of personal jurisdiction over a defendant 

in a civil action in state court, see Bristol-Meyers Squibb Co. v. 

Superior Court of California, San Francisco County, 137 S. Ct. 

1773 (2017), some commentators have called for amending 

Rule 4(k)(1)(A). The commentators argue that, due to these recent 

developments, an amendment to the rule is necessary to ensure that 
- 37 -

it does not become a bar to the beneficial aggregation of claims 

in federal court that it was not originally intended to be. See

Scott Dodson, Personal Jurisdiction and Aggregation, 113 Nw. U. L. 

Rev. 1, 37-40 (2018); see also Stephen E. Sachs, How Congress 

Should Fix Personal Jurisdiction, 108 Nw. U. L. Rev. 1301, 1316 

(2014).

The commentators assert that for most of the rule's life 

Fourteenth Amendment-based due process limits on the exercise of 

personal jurisdiction in state court were not as strict as the 

Supreme Court of the United States has deemed them to be in recent 

rulings, such as Bristol-Meyers Squibb. See Dodson, supra, at 37. 

The commentators also note that Fifth Amendment-based due process 

limits on the exercise of personal jurisdiction in federal court 

are not nearly as strict as the Fourteenth Amendment's parallel 

limits in state court have been held to be. See A. Benjamin 

Spencer, The Territorial Reach of Federal Courts, 71 Fla. L. Rev. 

979, 990-91 (2019). The commentators thus contend that there is 

no good reason to saddle federal courts -- as Rule 4(k)(1)(A) now 

saddles them -- with the current limits on the exercise of personal 

jurisdiction that the federal Constitution imposes only on state 

courts. See, e.g., the sources cited in Dodson, supra, at 36 

n.216. 

Nonetheless, no such amendment to Rule 4(k)(1)(A) has 

been made to this point, and defendants are invoking the rule with 
- 38 -

seemingly greater frequency to request that federal courts dismiss 

claims based on limits on the exercise of personal jurisdiction 

imposed on state courts by the Fourteenth Amendment's Due Process 

Clause. See, e.g., Lyngaas v. Curaden Ag, 992 F.3d 415 (6th Cir. 

2021); Molock v. Whole Foods Mkt. Grp., Inc., 952 F.3d 293 (D.C. 

Cir. 2020). Indeed, this case reflects the trend, as the defendant 

here -- Day & Zimmermann -- contends that Rule 4(k)(1)(A) bars the 

United States District Court for the District of Massachusetts 

from exercising personal jurisdiction over certain claims solely 

because of constraints that a state court in Massachusetts would 

face in exercising personal jurisdiction over those same claims by 

virtue of recent Supreme Court precedent interpreting the 

Fourteenth Amendment's Due Process Clause. 

Specifically, Day & Zimmermann contends that, because of 

the interaction between Rule 4(k)(1)(A) and the Fourteenth 

Amendment-based due process limits on personal jurisdiction over 

a defendant in state court that were relatively recently set forth 

in Bristol-Myers Squibb, the District Court must dismiss the claims 

of certain of the individuals who have filed written consent forms 

that signal their intention to participate in the collective action 

that the named plaintiff here, John Waters, has initiated by the 

inclusion of a Fair Labor Standards Act (FLSA) collective action 

claim in his complaint pursuant to section 216(b) of the FLSA. In 

that complaint, Waters asserts, alongside his own solely 
- 39 -

individual claim under the FLSA, an FLSA claim "on behalf of" what 

his complaint refers to as a "putative class" of certain former 

employees of Day & Zimmermann who are "similarly situated" to him. 

See 29 U.S.C. § 216(b). 

II.

In rejecting Day & Zimmermann's contention that the 

District Court erred in denying the motion to dismiss the claims 

just described, the majority relies on the text and purposes of 

Rule 4(k)(1)(A). The majority contends based on these interpretive 

sources that the rule is best read to restrict the scope of the 

condition that it sets forth that makes it so that a summons 

"establishes" personal jurisdiction in federal court over the 

defendant who is served with it -- namely, the condition that the 

defendant "is subject to the jurisdiction of a [state] court of 

general jurisdiction in the state where the" civil action 

commenced. 

In the majority's view, Rule 4(k)(1)(A) must be read to 

subject that condition to an implicit time-of-service-based 

limitation on its scope. The majority therefore rejects the 

contention -- pressed vigorously by Day & Zimmermann -- that the 

rule provides that the condition that it sets forth must be 

satisfied for the life of the suit. 

In other words, the majority embraces a reading of the 

rule in which that condition need be satisfied only at the time 
- 40 -

that the summons is served. For this reason, the majority 

concludes that the condition need not be satisfied, as Day & 

Zimmermann would have it, as to any claims and plaintiffs that are 

added after the summons has been served. 

The result is that, under the majority's reading of Rule 

4(k)(1)(A), Fourteenth Amendment-based due process limits on 

personal jurisdiction in state court -- including those set forth 

in Bristol-Myers Squibb -- can have no application to the claims 

of those individuals here who have filed written forms in which 

they have consented to participate in Waters's collective action 

pursuant to section 216(b) of the FLSA. As the majority explains, 

such due process limits have no application to those claims by 

virtue of the Fourteenth Amendment itself, given that the suit is 

being brought in federal court. And, as the majority emphasizes, 

those limits also have no application to those claims by virtue of 

Rule 4(k)(1)(A), because the individuals who filed the written 

forms in which they consented to participate in Waters's FLSA 

collective action did so only after Waters had served Day & 

Zimmermann with the summons. 

Thus, according to the majority, it follows that the 

only bar that could potentially prevent the District Court from 

exercising personal jurisdiction over Day & Zimmermann as to the 

claims at issue in this appeal is the bar that the Due Process 

Clause of the Fifth Amendment might impose. But, as the majority 
- 41 -

rightly concludes, Day & Zimmermann has made no argument that the 

Fifth Amendment's Due Process Clause does impose any such bar here. 

For that reason, the majority affirms the District Court's denial 

of the motion to dismiss that is before us in this appeal.

III.

The majority's time-of-service-based reading of Rule 

4(k)(1)(A) is internally coherent. The text of that rule is at 

least arguably ambiguous as to whether the summons "establishes" 

personal jurisdiction over the defendant for the life of the suit 

only if that defendant "is" subject to the jurisdiction of the 

state court for the life of the suit or whether the summons 

"establishes" personal jurisdiction over the defendant for the 

life of the suit so long as that defendant "is" subject to the 

jurisdiction of a state court at the time that the summons is 

served. 

The majority's time-of-service-based reading of the rule 

also accords with the intuition that it would be odd for a rule 

that seeks only to describe the means for making service of process 

effective to make those means dependent on events that might occur 

after service has been made. It is an arguable virtue of the 

majority's reading of the rule that one need only attend to what 

has occurred up until service has been completed to know whether 

such service has been effective.
- 42 -

The majority's reading of the rule also has going for it 

one more thing: it helps to ensure that the rule will not prove to 

be the seemingly unintended obstacle to the beneficial aggregation 

of claims in federal court that has provoked some commentators to 

call for its amendment. That is because, under the majority's 

reading of the rule, a plaintiff may ensure the beneficial 

aggregation of such claims in most cases merely by amending the 

complaint after the summons has been served to include any claims 

over which a state court would not be able to exercise personal 

jurisdiction. 

These features of the majority's reading of the rule do 

not, however, spare it from being controversial. The reading is 

in apparent tension with the broader, life-of-the-suit reading of 

the rule's condition that would appear to undergird the 

commentators' calls for its amendment. It would be strange for 

these commentators to have called for such an amendment if they in 

fact share the majority's view that the rule's deleterious effects 

on the beneficial aggregation of claims plainly can be overcome at 

present by a means as simple as the post-summons amendment of the 

complaint that was operative at the time that the summons was 

served. See A. Benjamin Spencer, Out of the Quandary: Personal 

Jurisdiction over Absent Class Members Explained, 39 Rev. Litig. 

31, 43 (2019) ("It would be preposterous to suggest 

that . . . amended complaints . . . may evade the restrictions 
- 43 -

applicable to claims contained within complaints served under Rule 

4, subject only to the limits of the Fifth Amendment's due process 

clause. Were such the case, the ability to amend would provide a 

gaping loophole to the ordinary territorial restrictions on 

federal court jurisdiction that Rule 4(k) imposes."). 

The majority's reading of Rule 4(k)(1)(A) also directly 

conflicts, as the majority itself acknowledges, with that of other 

circuits. See Canaday v. Anthem Cos., 9 F.4th 392, 400 (6th Cir. 

2021) ("Even with amended complaints . . . the district court 

remains constrained by Civil Rule 4(k)'s -- and the host 

State's -- personal jurisdictional limitations."); see also

Vallone v. CJS Solutions Grp., LLC, 9 F.4th 861, 865 (8th Cir. 

2021). Nor am I aware of any other case in which any court 

(including our own) has ever read Rule 4(k)(1)(A) in the narrow, 

time-of-service-limited way that the majority reads it. 

Indeed, the common (if, perhaps unreflective) practice 

of federal courts under this rule appears, as best I can tell, to 

have been to apply Fourteenth Amendment-based (rather than Fifth 

Amendment-based) due process limits on personal jurisdiction 

throughout a suit's duration, and so even as to later-added claims 

and plaintiffs. See, e.g., Old Republic Ins. Co. v. Cont'l Motors, 

Inc., 877 F.3d 895, 902-03 (10th Cir. 2017) (noting that the 

plaintiff's amended complaint is "the operative one" for the 

purpose of analyzing a Rule 12(b)(2) motion to dismiss for lack of 
- 44 -

personal jurisdiction); see also Spencer, Out of the Quandary, 

supra, at 43 ("There is no question that -- notwithstanding that 

such amended complaints are not served with a summons under Rule 

4 -- new claims appearing in amended complaints must satisfy the 

jurisdictional constraints imposed by Rule 4(k); courts regularly 

apply Rule 4(k)(1)(A) limitations to the claims appearing in

amended complaints.").16 Thus, it would appear that, given the way 

that the majority now reads the rule, federal courts in our circuit 

will have to change how they have been doing things in many cases, 

and in all cases that involve state law claims. For, under the 

majority's reading, they will have to assess personal jurisdiction 

in those cases with exclusive reference to Fifth Amendment-based 

16 The majority appears to suggest that even if Rule 

4(k)(1)(A) applies to state law claims added post-summons, it does 

not apply to parties asserting federal claims post-summons. Maj. 

Op. at 31 n.10. But, nothing in the text of the rule distinguishes 

between the rule's application to state law claims and its 

application to federal ones, even though the rule plainly applies 

to federal claims generally, see Walden v. Fiore, 571 U.S. 277, 

283 (2014) (applying Rule 4(k)(1)(A) to a federal law claim), and 

even though other parts of Rule 4(k) do expressly distinguish 

between state and federal claims, see Fed. R. Civ. P. 4(k)(2) 

(drawing that very distinction by way of reference to "a claim 

that arises under federal law"). Nor does anything in the text of 

the rule distinguish between the rule's application to claims and 

its application to parties. Thus, it would appear to be the case 

that however the rule applies to later-added state law claims must 

be how it applies to later-added parties asserting federal claims. 

I add only that the rule's failure to draw a distinction between 

state and federal claims is precisely what has motivated 

commentators to recommend that the rule be amended to ensure that 

federal claims (including, it seems, ones brought by later-added 

parties) are not subject to the rule in the same way that state 

law claims are. See Dodson, supra, at 37-40. 
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due process limits (and thus to work their way through all the 

legal complexity that may arise from their doing so in cases 

involving state law claims) despite their seeming common practice 

of not using that lens except in certain classes of cases that 

involve federal claims, see Fed. R. Civ. P. 4(k)(1)(C); id.

4(k)(2), in which the degree of legal complexity that then arises 

from using that same lens is much less.

IV.

In my view, there is no reason to decide in this case 

whether the majority is right to read Rule 4(k)(1)(A) to be subject 

to the implicit time-of-service limitation that it discerns on the 

scope of the condition that the rule sets forth. Given the 

embryonic state of the FLSA collective action that is before us 

and the interlocutory nature of this appeal, I would let the suit 

proceed apace in the District Court rather than attempt to resolve 

on interlocutory review this substantial question of first 

impression in our Circuit about the best way to read 

Rule 4(k)(1)(A). In fact, it seems to me that there is special 

reason to follow this more restrained course here, because the 

resolution of the question that the majority chooses to decide in 

this case's preliminary posture will be binding in our Circuit not 

only in cases that concern collective actions under the FLSA but 

also in a whole range of cases that also implicate Rule 4(k)(1)(A) 

but that have nothing to do with FLSA collective actions at all. 
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I note that the more cautious approach that I favor, 

which would cause me to dismiss this interlocutory appeal, accords 

with our general reluctance to hear appeals from denials of motions 

to dismiss precisely because such appeals necessarily come to us 

on an interlocutory basis. See Caraballo-Seda v. Municipality of 

Hormigueros, 395 F.3d 7, 8 (1st Cir. 2005) (acknowledging "our 

general rule prohibiting interlocutory appeals from the denial of 

a motion to dismiss"). Nor do I see a reason to deviate from this 

tried-and-true stance by making a case-specific exception to it 

here, even if there might be good reason to make such an exception 

in some cases that involve requests to appeal from denials of 

motions to dismiss that are made in connection with collective 

actions that are brought under section 216(b) of the FLSA. 

The underlying (and unsuccessful) motion to dismiss that 

is at issue here was made before the named plaintiff who filed the 

complaint asserting the FLSA collective action claim, Waters, has 

even moved to certify the putative class of "similarly situated" 

employees on whose behalf he seeks to sue in bringing that claim. 

See 29 U.S.C. § 216(b). Thus, as Waters pointed out in opposing 

interlocutory review of the denial of that motion here, still more 

opt-ins may consent to participate in the collective action that 

is at issue even after a ruling on the merits of this appeal. Nor 

do we know for certain at this juncture -- as we would if we waited 

for a motion to certify to be filed -- that Waters will seek to 
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bring a collective FLSA action on behalf of every present opt-in, 

let alone on behalf of each of those opt-ins who would be permitted 

to sue under the majority's construction of Rule 4(k)(1)(A). Cf.

Molock, 952 F.3d at 298-99 ("[P]rior to . . . certification, the 

potential [collective action] and their potential claims are just 

that: potentials."). And, of course, it is up to Waters in the 

first instance whether any individual who might wish to opt in and 

participate in the collective action may do so, precisely because 

he is bringing it. 

Reinforcing the reason to adhere in this case (given its 

nascent nature) to our usual unwillingness to resolve an appeal 

from a denial of a motion to dismiss is the fact that Day & 

Zimmermann has made little more than a conclusory showing about 

the need for us to weigh in now on the District Court's ability to 

exercise personal jurisdiction over it as to the claims of members 

of what at this point is only a "putative" class of claimants. 

That Day & Zimmermann has not made a substantial showing of an 

unusual need for resolution of that question this early in this 

case is especially significant because it is not as if Day & 

Zimmermann is presently at risk of being held liable to any of the 

so-called opt-ins who might end up being in that still, as-yetdefined class. 

If a default judgment were entered against Day & 

Zimmermann at this point in the case, I do not see how any of those 
- 48 -

individuals who thus far have filed written consent forms to 

participate in Waters's collective action under the FLSA could 

benefit from that judgment any more than they could if they had 

not filed such forms. That is precisely because the named 

plaintiff who is bringing the collective action under the FLSA, 

Waters, has not yet moved for certification of a collective action 

on their behalf -- or, for that matter, on behalf of anyone. Cf.

Rodriguez v. Almighty Cleaning, Inc., 784 F. Supp. 2d 114, 129 

(E.D.N.Y. 2011) (granting a motion for certification of an FLSA 

collective action simultaneously with a motion for default 

judgment). 

Thus, while I recognize that an earlier panel of our 

Court granted the petition for certification of the interlocutory 

appeal pursuant to 28 U.S.C. § 1292(b), see Waters v. Day & 

Zimmermann NPS, Inc., No. 20-1831 (1st Cir. Oct. 14, 2020), I am 

convinced -- now that we have had full briefing and oral 

argument as that panel did not -- that the petition was 

improvidently granted. See Caraballo-Seda, 395 F.3d at 9. I am 

aware in so concluding of the out-of-circuit precedent that has 

permitted the interlocutory review of the merits of a ruling on a 

motion to dismiss the claims of individuals who had opted in to a 

named plaintiff's collective action claim under the FLSA. But, 

the cases that have permitted such an appeal were ones not only in 

which that appeal was from a grant of the motion to dismiss but 
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also in which the appeal was from a ruling on a motion to dismiss 

that was made at the time of (or in the wake of) a motion to 

certify a class of similarly situated persons on behalf of whom 

the named plaintiff was bringing the collective action under the 

FLSA. See Canaday, 9 F.4th at 395; see also Vallone v. CJS 

Solutions Grp., LLC, 9 F.4th 861, 864 (8th Cir. 2021) (involving 

appellate review of a district court's order limiting an FLSA 

collective action to "employees 'who engaged in out-of-town travel 

to or from a Minnesota jobsite for [the defendant] or who resided 

in Minnesota'"). I am not aware of any precedent prior to this 

case in which a court has permitted interlocutory review of a 

denial of a motion to dismiss such opt-in claims in an FLSA 

collective action, let alone any such precedent in a case of that 

sort in which the denial of the motion to dismiss preceded -- as 

it does here -- a motion to certify the class of "similarly 

situated" persons on whose behalf the named plaintiff is bringing 

the collective action under the FLSA.17 

17 I note that, in other cases in which, like here, the 

named plaintiff had made no motion to certify the class of 

"similarly situated" individuals on whose behalf the FLSA 

collective action would be brought, other district courts have 

denied motions to certify for interlocutory appeal under 28 U.S.C. 

§ 1292(b) the district court's order denying a Fed. R. Civ. P. 

12(b)(2) motion to dismiss the claims of opt-ins. See Murphy v. 

Labor Source, LLC, No. 19-cv-1929, 2021 WL 527932 (D. Minn. Feb. 

12, 2021); Seiffert v. Qwest Corp., No. CV-18-70-GF-BMM, 2019 WL 

859045 (D. Mont. Feb 22, 2019). 
- 50 -

Accordingly, I would dismiss this appeal. By doing so, 

we would be following our usual wait-and-see approach when 

confronted with a request to decide an appeal from a denial of a 

motion to dismiss, and, by doing so, we also would be ensuring 

that we would not be deciding a major question about the meaning 

of the Federal Rules of Civil Procedure in a case in which it may 

turn out not to be necessary for us to decide that question at 

all.18 

18 The majority does undertake an extensive analysis of 

whether the opt-ins in an FLSA collective action are partyplaintiffs who can appeal a ruling denying certification of a 

collective action on their behalf. See Campbell v. City of Los 

Angeles, 903 F.3d 1090, 1104-06 (9th Cir. 2018); Mickles v. Country 

Club Inc., 887 F.3d 1270, 1278 (11th Cir. 2018). But, I do not 

see how those precedents are relevant to the question that is my 

concern, which pertains to whether we should be entertaining this 

interlocutory appeal when no motion for certification has even 

been filed, let alone denied. I do also note that even if the

majority is right to endorse the precedents that it relies on about 

the party-plaintiff status of opt-ins, the wait-and-see approach 

that I favor avoids the oddity of resolving on appeal the merits 

of a motion to dismiss claims that belong to individuals who are 

not even listed in the case's caption as parties to the appeal. 

My concern with our choosing to resolve such a motion in this odd 

posture is heightened by the fact that nothing in Day & 

Zimmermann's briefing to this Court indicates that Day & Zimmermann

is seeking to dismiss Waters's collective action claim itself (even 

in part), as the briefing by Day & Zimmermann advances arguments 

for dismissing only the claims of the individual opt-ins, none of 

which are Waters's claims alone. Cf. Molock, 952 F.3d at 300. In 

any event, insofar as Day & Zimmermann could be understood to be 

seeking to dismiss not those claims directly but only Waters's

collective action claim insofar as it is brought on the opt-ins'

behalf, the appeal remains interlocutory and thus still should be 

dismissed for all the reasons that I have given.