In the

    United States Court of Appeals
                 For the Seventh Circuit
                     ____________________
No. 24-1626
THOMAS ANDERSON, et al.,
                                                Plaintiffs-Appellants,
                                 v.

UNITED AIRLINES, INC., et al.,
                                               Defendants-Appellees.
                     ____________________

         Appeal from the United States District Court for the
           Northern District of Illinois, Eastern Division.
           No. 23 C 989 — Matthew F. Kennelly, Judge.
                     ____________________

     ARGUED NOVEMBER 14, 2024 — DECIDED JUNE 9, 2025
                ____________________

    Before JACKSON-AKIWUMI, PRYOR, and MALDONADO, Cir-
cuit Judges.
    PRYOR, Circuit Judge. Plaintiffs are employees of United
Airlines, Inc., including pilots, flight attendants, ramp service
workers, mechanics, technicians, and customer service repre-
sentatives. They challenge United’s COVID-19 vaccination
mandate and masking requirement issued in 2021. The dis-
trict court dismissed Plaintiffs’ claims with prejudice after
2                                                  No. 24-1626

finding Plaintiffs had not stated any viable claim for relief de-
spite sufficient opportunity to do so. We affirm.
                     I.   BACKGROUND

    A. Factual Background

    For the purposes of this appeal, we accept as true the facts
alleged by Plaintiffs. Bronson v. Ann & Robert H. Lurie Child.’s
Hosp. of Chi., 

, 441 (7th Cir. 2023).
   On August 6, 2021, United announced it would require
employees to receive vaccination for COVID-19. It created an
online system for employees to request religious or medical
exemptions from the vaccination requirement. It required em-
ployees to submit exemption requests online by August 31,
2021. Employees who were not exempt from the requirement
were expected to receive their first dose of the COVID-19 vac-
cine by September 27, 2021.
    United also required employees to provide proof of vac-
cination by uploading a copy of their vaccination record to
United’s employee database. In early September, United sent
postcards to employees who had not yet provided proof. The
postcard stated, “Our records indicate that you have not up-
loaded your COVID-19 vaccine information,” and further in-
structed that “unvaccinated employees without a reasonable
accommodation will be separated from United.” Plaintiffs
were among the employees to receive these postcards.
   On September 30, 2021, United announced a new mask
policy, pursuant to which unvaccinated employees—includ-
ing those who sought an exemption—were required to wear
KN95 or N95 masks.
No. 24-1626                                                     3

    Plaintiffs allege that despite having submitted or “at-
tempted to submit” religious accommodation requests,
United either fired them, placed them on unpaid leave, or oth-
erwise harmed their careers by subjecting them to a hostile
work environment. For example, plaintiff Thomas Anderson
alleges that he was “constructively discharged” due to his ex-
ercise of his religious accommodation. Plaintiff Paul Rozell al-
leges that he was terminated for not receiving the COVID-19
vaccine despite trying to apply for a religious accommoda-
tion. Rozell alleges he missed United’s deadline for accommo-
dation requests because he was out of town. For most of the
remaining plaintiffs, however, the complaint fails to provide
individualized allegations regarding their circumstances.
   B. Procedural Background
    Plaintiffs brought federal and state law claims against
United and more than two dozen of its executives, officers,
and board members. Defendants moved to dismiss for failure
to state a claim, and the district court granted Plaintiffs an ex-
tension to file a response. Plaintiffs did not respond but in-
stead filed a proposed amended complaint. Pursuant to Fed-
eral Rule of Civil Procedure 15(a), the district court construed
the amended complaint as a motion for leave to file an
amended complaint.
    After briefing from the parties, the district court denied
the motion. In so doing, it addressed each of Plaintiffs’ twelve
claims. With respect to many of those claims, the court found
dispositive Plaintiffs’ failure to respond to substantive argu-
ments offered by United. For other claims, however, it identi-
fied deficiencies in the proposed amended complaint that
needed to be corrected to adequately state a claim. It afforded
Plaintiffs additional time to file a new proposed amended
4                                                   No. 24-1626

complaint and instructed that failure to do so would warrant
entry of judgment for United.
    Plaintiffs filed a second proposed amended complaint
which the district court again construed as a motion for leave
to amend. Following another round of briefing, the district
court denied the motion as futile. Reasoning that Plaintiffs
“had sufficient opportunities to attempt to state viable
claims” but “failed to do so,” the court dismissed the action
with prejudice. Plaintiffs appeal.
                     II.   DISCUSSION
    District courts should afford a plaintiff leave to amend a
complaint “when justice so requires.” Fed. R. Civ. P. 15(a).
However, a district court may deny a motion for leave to
amend “if the proposed amendment fails to cure the deficien-
cies in the original pleading, or could not survive a second
motion to dismiss.” Crestview Vill. Apartments v. U.S. Dep’t of
Hous. & Urban Dev., 

 (7th Cir. 2004) (internal
quotation marks and citation omitted). “Where a plaintiff re-
peatedly fails to cure deficiencies, the district court enjoys
‘broad discretion’ to deny leave to amend.” Knowlton v. City
of Wauwatosa, 

, 520 (7th Cir. 2024) (quoting Arre-
ola v. Godinez, 

 (7th Cir. 2008)).
    “Generally, denials of leave to amend are reviewed for
abuse of discretion.” Runnion ex rel. Runnion v. Girl Scouts of
Greater Chi. and Nw. Ind., 

 (7th Cir. 2015). But
where a district court denies a motion for leave to amend as
futile, our review is de novo, and we ask whether the pro-
posed amended complaint would fail to state a claim. 

 “Ac-
cordingly, our review for abuse of discretion of futility-based
No. 24-1626                                                                  5

denials includes de novo review of the legal basis for the futil-
ity.” 

   On appeal, Plaintiffs argue the district court’s dismissal
was in error because their proposed second amended com-
plaint adequately stated a claim for (1) violation of the Federal
Food, Drug, and Cosmetic Act (FDCA); (2) invasion of pri-
vacy under Illinois law; (3) negligence under Illinois law; (4)
violation of the Illinois Whistleblower Act; and (5) multiple
violations of Title VII.1
    A. FDCA, Invasion of Privacy, and Negligence Claims

    The district court rejected Plaintiffs’ FDCA, invasion of
privacy, and negligence claims on multiple grounds, includ-
ing forfeiture. Specifically, in regard to Plaintiffs’ FDCA
claim, the court held that Plaintiffs had forfeited their right to
continue litigating the FDCA claim because they failed to re-
spond in the first round of briefing to United’s argument that
the FDCA contained no private right of action. The district
court similarly found Plaintiffs’ invasion of privacy and neg-
ligence claims forfeited because Plaintiffs had failed to re-
spond in the earlier round of briefing to United’s arguments

1
  Plaintiffs’ briefing on appeal does not substantively discuss their other
claims, including for intentional and negligent infliction of emotional dis-
tress under Illinois law, violations of the United States Constitution under

 and Bivens, and violations of the Genetic Information
Nondiscrimination Act (GINA), 42 U.S.C. § 2000ff-1(a). Although Plain-
tiffs embed cursory references to constitutional law within their discus-
sion of non-constitutional claims, these references do not qualify as cog-
nizable legal arguments. Shipley v. Chicago Bd. of Election Comm’rs, 

, 1062–63 (7th Cir. 2020); Lekas v. Briley, 

, 614 n.8 (7th Cir.
2005). We therefore find waived Plaintiffs’ emotional distress, constitu-
tional, and GINA claims.
6                                                  No. 24-1626

that its postcards and mask mandate did not publicly disclose
any private fact.
    Plaintiffs do not engage with the district court’s findings
of forfeiture, despite forfeiture being an independent basis on
which the district court rejected Plaintiffs’ claims. Where a
party “lose[s] in the district court on multiple grounds,” such
as “forfeiture and the merits,” that party “must contest all on
appeal; prevailing on one won’t suffice.” United States v.
Boliaux, 

 (7th Cir. 2019); see also Klein v.
O’Brien, 

 (7th Cir. 2018). Because forfeiture
went unaddressed on appeal, and because forfeiture was an
independent ground on which the district court rejected
Plaintiffs’ FDCA, invasion of privacy, and negligence claims,
we find Plaintiffs have waived their ability to appeal these
claims.
    B. Illinois Whistleblower Act Claim
   The Illinois Whistleblower Act prohibits an employer
from “retaliat[ing] against an employee for refusing to partic-
ipate in an activity that would result in a violation of a State
or federal law, rule, or regulation.” Perez v. Staples Cont. &
Com. LLC, 

, 574 (7th Cir. 2022) (quoting 740 ILL.
COMP. STAT. ANN. 174/20 (2009)).
   Plaintiffs’ proposed amended complaint alleges that
United retaliated against pilots who refused the COVID-19
vaccine and appears to suggest that any pilot who received a
COVID-19 vaccine would be participating in an illegal act un-
der 

. That regulatory provision prohibits a
person from “act[ing] as pilot in command” when, among
other things, the person knows of “any medical condition that
would make the person unable to meet the requirements for
No. 24-1626                                                      7

the medical certificate necessary for the pilot operation.” 

(a)(1).
    The district court correctly concluded Plaintiffs did not
state a claim pursuant to this theory. Neither Plaintiffs’ pro-
posed amended complaint nor briefing on appeal shows how
receipt of a COVID-19 vaccine would render the recipient un-
able to qualify for “the medical certificate necessary for [] pilot
operation.” 

     We also acknowledge that Plaintiffs alternatively sought
to support their Whistleblower Act claim with allegations re-
lating to Title VII. However, the district court found forfeited
any argument that the Whistleblower Act claim could be
based on Title VII, as Plaintiffs’ briefing in support of their
proposed amended complaint did not discuss this theory at
all. Because Plaintiffs’ appeal does not engage with the district
court’s finding of forfeiture, we affirm the reasoning of the
district court. See Boliaux, 

.
   C. Title VII Claims
    Plaintiffs’ remaining three claims on appeal were brought
under Title VII, 42 U.S.C. § 2000e-2. These claims allege a fail-
ure to accommodate religious beliefs, disparate treatment
based on religion, and a hostile work environment based on
religion. The district court dismissed each claim because
Plaintiffs did not show that any plaintiff had received a right-
to-sue letter from the U.S. Equal Employment Opportunity
Commission (EEOC), which is a prerequisite to a lawsuit un-
der Title VII; and, alternatively, because Plaintiffs did not ad-
equately plead any Title VII claim.
   Plaintiffs offer a broad statement on appeal that, except for
one plaintiff, each plaintiff has either received a right-to-sue
8                                                      No. 24-1626

letter or is “currently in the process of receiving it.” In the al-
ternative, they argue they should be excused from this ex-
haustion requirement because their case raises constitutional
questions and because of the stress they incurred from the un-
derlying events in this lawsuit.
    “Before bringing a Title VII claim, a plaintiff must first ex-
haust his administrative remedies by filing charges with the
EEOC and receiving a right to sue letter.” Chaidez v. Ford Mo-
tor Co., 

, 1004 (7th Cir. 2019); see also Conner v. Ill.
Dep’t of Nat. Res., 

 (7th Cir. 2005) (obtaining a
right-to-sue letter is a “prerequisite[] for bringing a Title VII
claim”). A “complaint may be deficient and subject to dismis-
sal if the plaintiff lacks a right-to-sue letter.” Worth v. Tyer, 

 (7th Cir. 2001).
    Neither Plaintiffs’ proposed amended complaint nor ap-
pellate briefing reflect that any specific plaintiff obtained a
right to sue letter. Moreover, Plaintiffs do not provide author-
ity to support the proposition that a plaintiff may proceed
with a Title VII action by offering a blanket assertion that they
are “in the process of receiving” right-to-sue letters, or that
latent constitutional issues and stress incurred in litigation are
valid grounds for overlooking the absence of a right-to-sue
letter. See Baldwin Cnty. Welcome Ctr. v. Brown, 

 (1984) (instructing that courts must strictly enforce “[p]ro-
cedural requirements established by Congress for gaining ac-
cess to the federal courts”). And while we acknowledge that
receipt of a right-to-sue letter prior to the district court’s dis-
missal of a case may “cure[] any deficiency in the original
complaint,” Worth, 

, Plaintiffs likewise do not
show that they received right-to-sue letters prior to the dis-
trict court’s dismissal of this case.
No. 24-1626                                                     9

   Because we affirm on the issue of exhaustion, we need not
reach the district court’s alternate grounds for dismissing
Plaintiffs’ Title VII claims.
                    III.   CONCLUSION
     We agree with the district court that Plaintiffs’ claims are
either improperly preserved or inadequately pled. We further
find the district court did not err in declining to afford Plain-
tiffs an additional opportunity to file a proposed amended
complaint, as Plaintiffs do not “identify how [they] would
cure defects in [their] complaint.” Pension Tr. Fund for Operat-
ing Eng’rs v. Kohl’s Corp., 

 (7th Cir. 2018). For
these reasons, we AFFIRM.