FOR PUBLICATION

UNITED STATES COURT OF APPEALS

FOR THE NINTH CIRCUIT

LINDSAY HECOX; JANE DOE, with her 

next friends Jean Doe and John Doe, 

Plaintiffs-Appellees, 

 v. 

BRADLEY LITTLE, in his official capacity 

as Governor of the State of Idaho; SHERRI 

YBARRA, in her official capacity as the 

Superintendent of Public Instruction of the 

State of Idaho and as a member of the Idaho 

State Board of Education; INDIVIDUAL 

MEMBERS OF THE STATE BOARD OF 

EDUCATION, in their official capacities; 

BOISE STATE UNIVERSITY; MARLENE 

TROMP, in her official capacity as President 

of Boise State University; INDEPENDENT 

SCHOOL DISTRICT OF BOISE CITY, # 1; 

COBY DENNIS, in his official capacity as 

superintendent of the Independent School 

District of Boise City #1; INDIVIDUAL 

MEMBERS OF THE BOARD OF 

TRUSTEES OF THE INDEPENDENT 

SCHOOL DISTRICT OF BOISE CITY, # 1; 

in their official capacities; INDIVIDUAL 

MEMBERS OF THE IDAHO CODE 

COMMISSION, in their official capacities, 

Defendants-Appellants, 

and 

No. 20-35813 

D.C. No. 1:20-cv-00184-DCN 

AMENDED OPINION

FILED

JUN 7 2024

MOLLY C. DWYER, CLERK

U.S. COURT OF APPEALS
2 

MADISON KENYON; MARY 

MARSHALL, 

Intervenors.

LINDSAY HECOX; JANE DOE, with her 

next friends Jean Doe and John Doe, 

Plaintiffs-Appellees, 

 v. 

BRADLEY LITTLE, in his official capacity 

as Governor of the State of Idaho; SHERRI 

YBARRA, in her official capacity as the 

Superintendent of Public Instruction of the 

State of Idaho and as a member of the Idaho 

State Board of Education; INDIVIDUAL 

MEMBERS OF THE STATE BOARD OF 

EDUCATION, in their official capacities; 

BOISE STATE UNIVERSITY; MARLENE 

TROMP, in her official capacity as President 

of Boise State University; INDEPENDENT 

SCHOOL DISTRICT OF BOISE CITY, # 1; 

COBY DENNIS, in his official capacity as 

superintendent of the Independent School 

District of Boise City #1; INDIVIDUAL 

MEMBERS OF THE BOARD OF 

TRUSTEES OF THE INDEPENDENT 

SCHOOL DISTRICT OF BOISE CITY, # 1; 

in their official capacities; INDIVIDUAL 

MEMBERS OF THE IDAHO CODE 

COMMISSION, in their official capacities, 

Defendants, 

and 

MADISON KENYON; MARY 

No. 20-35815 

D.C. No. 1:20-cv-00184-DCN 
3 

MARSHALL, 

Intervenors-Appellants.

Appeal from the United States District Court

for the District of Idaho

David C. Nye, Chief District Judge, Presiding

Argued and Submitted November 22, 2022

San Francisco, California

Opinion Filed August 17, 2023

Opinion Withdrawn April 29, 2024

Amended Opinion Filed June 7, 2024

Before: Kim McLane Wardlaw, Ronald M. Gould, and Morgan Christen, Circuit 

Judges.**

Opinion by Judge Wardlaw

WARDLAW, Circuit Judge:

In March 2020, Idaho enacted the Fairness in Women’s Sports Act, Idaho 

Code §§ 33-6201–06 (2020) (the “Act”), a first-of-its-kind categorical ban on the 

participation of transgender women and girls in women’s student athletics. At the 

time, Idaho had no history of transgender women and girls participating in 

competitive student athletics, even though Idaho’s interscholastic athletics 

organization allowed transgender girls to compete on female athletic teams under 

certain specified conditions. Elite athletic regulatory bodies, including the 

** Pursuant to General Order 3.2(h), Judge Christen has been drawn to 

replace Judge Kleinfeld in this matter. Judge Christen has reviewed the briefs and 

the record, and listened to the recording of the oral argument in this case.
4 

National Collegiate Athletic Association (NCAA) and the International Olympic 

Committee (IOC), also had policies allowing transgender women athletes to 

compete if they met certain criteria. The Act, however, bars all transgender girls 

and women from participating in, or even trying out for, public school female 

sports teams at every age, from primary school through college, and at every level 

of competition, from intramural to elite teams. See Idaho Code § 33-6203(1)–(2). 

The Act also provides a sex dispute verification process whereby any individual 

can “dispute” the sex of any student athlete participating in female athletics in the 

State of Idaho and require her to undergo intrusive medical procedures to verify 

her sex, including gynecological exams. See Idaho Code § 33-6203(3). Student 

athletes who participate in male sports are not subject to a similar dispute process.

Today, we decide only the question of whether the federal district court for 

the District of Idaho abused its discretion in August 2020 when it preliminarily 

enjoined the Act, holding that it likely violated the Equal Protection Clause of the 

Fourteenth Amendment. Because the Act subjects only students who wish to 

participate in female athletic competitions to an intrusive sex verification process

and categorically bans transgender girls and women at all levels from competing 

on “female[], women, or girls” teams, Idaho Code § 33-6203(2), and because the 

State of Idaho failed to adduce any evidence demonstrating that the Act is 

substantially related to its asserted interests in sex equality and opportunity for 
5 

women athletes, we affirm the district court’s grant of preliminary injunctive relief 

to Lindsay Hecox. We remand this case to the district court to reconsider the 

appropriate scope of injunctive relief in light of the Supreme Court’s decision in 

Labrador v. Poe, 144 S. Ct. 921 (2024). 

I. FACTUAL AND PROCEDURAL BACKGROUND

A.

As the district court noted, and as we recognize in this context, “such 

seemingly familiar terms as ‘sex’ and ‘gender’ can be misleading.” Hecox v. Little 

(Hecox I), 479 F. Supp. 3d 930, 945 (D. Idaho 2020) (quoting Doe ex rel. Doe v. 

Boyertown Area Sch. Dist., 897 F.3d 518, 522 (3d Cir. 2018)). We therefore adopt 

the terminology that has been employed throughout this case.

“Gender identity” is “the term used to describe a person’s sense of being 

male, female, neither, or some combination of both.”1 A person’s “sex” is 

typically assigned at birth based on an infant’s external genitalia, though “external 

genitalia” do not always align with other sex-related characteristics, which include 

“internal reproductive organs, gender identity, chromosomes, and secondary sex 

characteristics.” A “transgender” individual’s gender identity does not correspond 

to their sex assigned at birth, while a “cisgender” individual’s gender identity 

1

Joshua D. Safer & Vin Tangpricha, Care of Transgender Persons, 381 N. Eng. J. 

Med. 2451, 2451 (2019).
6 

corresponds with the sex assigned to them at birth. Around two percent of the 

population are born “intersex,” which is an umbrella term for people “born with 

unique variations in certain physiological characteristics associated with sex, such 

as chromosomes, genitals, internal organs like testes or ovaries, secondary sex 

characteristics, or hormone production or response.” Id. at 946 (internal quotation 

marks omitted).

Over 1.6 million adults and youth identify as transgender in the United 

States, or roughly 0.6 percent of Americans who are 13 years old or older.2 Youth 

ages 13 to 17 are significantly more likely to identify as transgender, with the 

Centers for Disease Control (CDC) estimating that roughly 1.8 percent of high 

school students identify as transgender. See Br. of Amici Curiae Am. Acad. of 

Pediatrics, et al. (“AAP Br.”) at 10. 

Transgender individuals often experience “gender dysphoria,” which is 

defined by the Fifth Edition, Text Revision, of the Diagnostic and Statistics 

Manual of Mental Disorders (DSM-5-TR) as a condition where patients experience 

“[a] marked incongruence between one’s experienced/expressed gender and 

assigned gender, of at least 6 months’ duration” that “is associated with clinically 

significant distress or impairment in social, occupation, or other important areas of 

2 See Jody L. Herman, Andrew R. Flores, Kathryn K. O’Neill, How Many Adults 

and Youth Identify as Transgender in the United States?, Williams Inst. 1 (2022). 
7 

functioning.”3 For over thirty years, medical professionals have treated individuals 

experiencing gender dysphoria following the protocols laid out in the Standards of 

Care for the Health of Transsexual, Transgender, and Gender Nonconforming 

People (Version 7), which were developed by the World Professional Association 

for Transgender Health (WPATH). AAP Br. at 19. 

B.

On March 16, 2020, Idaho passed House Bill 500 (“H.B. 500”), a categorical 

ban against transgender women and girls’ participation in any public-school 

funded women’s sports, enforced by subjecting all participants in female athletics 

to an intrusive sex verification process if their gender is disputed by anyone. See 

H.R. 500, 65th Leg., 2d Reg. Sess. (Idaho 2020). Although Idaho was the first 

state in the nation to issue such a ban, more than twenty other states have enacted 

similar—though perhaps not as potentially intrusive against all female athletes—

restrictions on female transgender athletes.4

3 See Am. Psychiatric Ass’n, Diagnostic and Statistics Manual of Mental 

Disorders 512–13 (5th ed., text rev. 2022).

4 Since the Act’s passage, twenty-four other states have passed laws or regulations 

limiting the participation of transgender students in women’s athletics. However, 

no other state appears to have enacted an enforcement mechanism for those 

restrictions like the sex dispute verification process in the Act. See Ala. Code 

§ 16-1-52 (2021); 4 Alaska Admin. Code § 06.115(b)(5)(D); Ariz. Rev. Stat. Ann. 

§ 15-120.02 (2022); Ark. Code Ann. § 6-1-107 (West 2021); Fla. Stat. Ann. 

§ 1006.205 (West 2021); Ind. Code Ann. § 20-33-13-4 (West 2022); Iowa Code 

Ann. § 261I.2 (West 2022); H.B. 2238, 2023 Leg. Sess. (Kan. 2023); Ky. Rev. 

Stat. Ann. § 164.2813 (West 2022); La. Stat. Ann. § 4:442 (2022); Miss. Code 
8 

In the United States, high school interscholastic athletics are generally 

governed by state interscholastic athletic associations, such as the Idaho High 

School Activities Association (IHSAA). The NCAA sets policies for member 

colleges and universities in Idaho and elsewhere, including Boise State University 

(BSU). Prior to the Act’s passage, IHSAA policy allowed transgender girls in 9–

12 athletics in Idaho to compete on girls’ teams after they had completed one year 

of hormone therapy suppressing testosterone under the care of a physician. At that 

time, NCAA policy similarly allowed transgender women attending member 

colleges and universities in Idaho (and elsewhere) to compete on women’s teams 

after one year of hormone therapy to suppress testosterone.5 Idaho itself had no 

record of transgender women and girls participating in competitive women’s 

sports. 

Ann. § 37-97-1 (West 2021); Mo. Rev. Stat. 163.048 (2023); Mont. Code Ann. 

§ 20-7-1306 (West 2021); H. 574 (N. C. 2023); Legis. Assemb. 1489, 68th Legis. 

Assemb., Reg. Sess. (N.D. 2023); Legis. Assemb. 1249, 68th Legis. Assemb., Reg. 

Sess. (N.D. 2023); Ohio Rev. Code § 3313.5320; Okla. Stat. Ann. tit. 70, § 27-106 

(West 2022); S.C. Code Ann. § 59-1-500 (2022); S.D. Codified Laws § 13-67-1 

(2022); Tenn. Code Ann. § 49-7-180 (2022); Tex. Educ. Code Ann. § 33.0834 

(West 2022); Utah Code Ann. § 53g-6-902 (West 2022); W. Va. Code Ann. § 18-

2-25d (West 2021); S. 92, 67th Leg., Gen. Sess. (Wyo. 2023).

5

In April 2023, the NCAA updated its policy to require that transgender studentathletes meet the “sport-specific standard[s] (which may include testosterone 

levels, mitigation timelines and other aspects of sport-governing body policies)” of 

the national governing body of that sport. See Press Release, NCAA, Transgender 

Student-Athlete Participation Policy (April 17, 2023), 

https://www.ncaa.org/sports/2022/1/27/transgender-participation-policy.aspx (last 

visited May 3, 2024).
9 

On February 13, 2020, Representative Barbara Ehardt introduced H.B. 500 

in the Idaho House of Representatives. At the first hearing on the bill, Ty Jones, 

Executive Director of the IHSAA, testified that no student in Idaho had ever 

complained about participation in public school sports by transgender athletes, and 

that no transgender athlete had ever competed in Idaho under the existing IHSAA 

policy. Representative Ehardt acknowledged that she had no evidence that any 

person in Idaho had ever disputed an athlete’s eligibility to play based on that 

athlete’s gender. 

After the Idaho House Committee approved the bill, Idaho Attorney General 

Lawrence Wasden warned in a written opinion letter to the House that H.B. 500 

raised serious constitutional questions due to the legislation’s disparate treatment 

of transgender and intersex athletes and the potential invasion of all female 

athletes’ privacy inherent in the sex dispute verification process. Nevertheless, the 

bill proceeded to a debate and passed on the House floor on February 26, 2020. 

After passage by the House, H.B. 500 was heard by the Senate State Affairs 

Committee and sent to the full Idaho Senate on March 10, 2020. On March 11, 

2020, the World Health Organization declared COVID-19 a pandemic and many 

states adjourned legislative sessions indefinitely. The Idaho Senate remained in 

session, however, and passed H.B. 500 as amended on March 16, 2020. The 
10 

House concurred in the Senate amendments on March 18, and the bill was 

delivered to Idaho Governor Bradley Little on March 19, 2020. 

As Governor Little considered the bill, critics questioned the legislation’s 

findings and legality. Professor Dorianne Lambelet Coleman, whose work on 

testosterone and athletics was cited in the legislative findings in support of the bill, 

wrote to Governor Little urging him to veto the bill and explaining that her 

research had been misinterpreted and misused in the legislative findings. 

Similarly, five former Idaho Attorneys General implored Governor Little to veto 

the Act, labeling it a “legally infirm statute.”6 Nonetheless, Governor Little signed 

H.B. 500 into law on March 30, 2020, and it went into effect on July 1, 2020. 

In enacting H.B. 500, the legislature made several findings based on 

Professor Coleman’s study, including “that there are ‘inherent [biological] 

differences between men and women,’” Idaho Code § 33-6202(1) (quoting United 

States v. Virginia (VMI), 518 U.S. 515, 533 (1996)), and that men have “higher 

natural levels of testosterone,” id. § 33-6202(4), which “have lifelong effects, 

including those most important for success in sport,” id. § 33-6202(5). Relying on 

Professor Coleman’s work, the legislature found that “[t]he benefit[] that natural 

6 See also Tony Park et al., 5 Former Idaho Attorneys General Urge Transgender 

Bill Veto, Idaho Statesman (Mar. 17, 2020), 

https://www.idahostatesman.com/opinion/readers-opinion/article241267071.html

(last visited May 23, 2023).
11 

testosterone provides to male athletes is not diminished through the use of puberty 

blockers and cross-sex hormones.” Id. § 33-6202(11). The legislature also found 

that “women’s performances at the high[est] level [of athletics] will never match 

those of men.” Id. § 33-6202(9) (quoting Valerie Thibault et al., Women and Men 

in Sport Performance: The Gender Gap Has Not Evolved Since 1983, 9 J. of 

Sports Sci. & Med. 214, 219 (2010)). The legislature concluded that “[h]aving 

separate sex-specific teams furthers efforts to promote sex equality” by “providing 

opportunities for female athletes to demonstrate their skill, strength, and athletic 

abilities, while also providing them with opportunities to obtain recognition and 

accolades, college scholarships, and numerous other long-term benefits that flow 

from success in athletic endeavors.” Id. § 33-6202(12). 

Three provisions of the Act are most salient to this appeal. First, the Act 

provides that “[i]nterscholastic, intercollegiate, intramural, or club athletic teams or 

sports” shall be organized “based on biological sex.” Id. § 33-6203(1). It 

specifically provides that: 

Interscholastic, intercollegiate, intramural, or club athletic teams or 

sports that are sponsored by a public primary or secondary school, a 

public institution of higher education, or any school or institution 

whose students or teams compete against a public school or institution 

of higher education shall be expressly designated as one (1) of the 

following based on biological sex: 

(a) Males, men, or boys; 

(b) Females, women, or girls; or 
12 

(c) Coed or mixed.

Id. The Act then provides that “[a]thletic teams or sports designated for females, 

women, or girls shall not be open to students of the male sex.” Id. § 33-6203(2) 

(the “categorical ban provision”). The Act’s provisions apply to all levels of 

competition in Idaho state schools, including elementary school and club teams, 

and do not include any limitation for transgender individuals who wish to 

participate on athletic teams designated for men. Moreover, the provisions apply 

not only to public schools, but also to nonpublic “school[s] or institution[s] whose 

students or teams compete against a public school or institution of higher 

education.” Id. § 33-6203(1).

Second, the Act creates a “sex verification” process to be invoked by any 

individual who wishes to “dispute” a student’s sex, providing that:

A dispute regarding a student’s sex shall be resolved by the school or 

institution by requesting that the student provide a health examination 

and consent form or other statement signed by the student’s personal 

health care provider that shall verify the student’s biological sex. The 

health care provider may verify the student’s biological sex as part of a 

routine sports physical examination relying only on one (1) or more of 

the following: the student’s reproductive anatomy, genetic makeup, or 

normal endogenously produced testosterone levels.

Id. § 33-6203(3) (the “sex dispute verification provision”). 

And third, the Act creates an enforcement mechanism to ensure compliance 

with its provisions by establishing a private cause of action for any student who is 
13 

“deprived of an athletic opportunity or suffers any direct or indirect harm as a 

result of a violation of [the Act].” Id. § 33-6205(1).

D.

On April 15, 2020, Lindsay Hecox (“Lindsay”), a transgender woman who 

wishes to try out for the BSU women’s track and cross-country teams, and Jane 

Doe (“Jane”), a cisgender woman who plays on high school varsity teams and 

feared that her sex would be “disputed” under the Act due to her masculine 

presentation, filed this lawsuit against Governor Little, Idaho Superintendent of 

Public Instruction Sherri Ybarra, and various school officials at both the high 

school and collegiate levels (collectively, “Idaho”). They sought a declaratory 

judgment that the Act violates Title IX and the United States Constitution, 

including the Equal Protection Clause, and preliminary and permanent injunctions 

against the Act’s enforcement, as well as an award of costs, expenses, and 

reasonable attorneys’ fees. 

On May 26, 2020, Madison (“Madi”) Kenyon and Mary (“MK”) Marshall 

(collectively, “the Intervenors”) were permitted to intervene in this case. 

Intervenors are cisgender women residing in Idaho and collegiate athletes who run 

track and cross-country on scholarship at Idaho State University. In 2019, both 

athletes competed against and lost to June Eastwood, a transgender woman athlete 
14 

at the University of Montana, and found it a “discouraging” and “deflating” 

experience. 

On April 30, 2020, Plaintiffs moved for preliminary injunctive relief based 

solely on their equal protection claims. The district court issued preliminary 

injunctive relief in August 2020, ruling that both Plaintiffs were likely to succeed 

on the merits of their equal protection claims and would suffer irreparable harm if 

the injunction was not granted, and that the balance of equities weighed in favor of 

an injunction. Idaho and the Intervenors (collectively, the “Appellants”) timely 

appealed. 

We first held oral argument in this appeal on May 3, 2021. At that time, 

Lindsay informed the court that she had tried out for and failed to make the 

women’s track team and that she subsequently withdrew from BSU classes in late 

October 2020. Because the parties’ arguments raised several unanswered factual 

questions as to whether Lindsay’s claim was moot, we remanded the case to the 

district court for further factual development and findings on justiciability 

questions on June 24, 2021. 

On July 18, 2022, the district court issued factual findings and concluded 

that Lindsay’s claim was not moot. We affirmed the district court’s determination 

that Lindsay’s claim was not moot in an order issued on January 30, 2023. See 

Hecox v. Little (Hecox II), No. 20-35813, 2023 WL 1097255, at *1 (9th Cir. Jan. 
15 

30, 2023).7 We then asked the parties to brief us on which claims remained for 

decision in this appeal and any intervening authority. The parties agree that the 

only issue that we must decide is whether the district court abused its discretion in 

issuing the preliminary injunction. 

II. STANDARD OF REVIEW

We review a district court’s grant of a preliminary injunction for an abuse 

of discretion. Puente Arizona v. Arpaio, 821 F.3d 1098, 1103 (9th Cir. 2016). 

That said, “legal issues underlying the injunction are reviewed de novo because a 

district court would necessarily abuse its discretion if it based its ruling on an 

erroneous view of law.” adidas Am., Inc. v. Skechers USA, Inc., 890 F.3d 747, 753 

(9th Cir. 2018) (quoting GoTo.com, Inc. v. Walt Disney Co., 202 F.3d 1199, 1204 

(9th Cir. 2000)); see also Sw. Voter Registration Educ. Project v. Shelley, 344 F.3d 

914, 918 (9th Cir. 2003). We do “not ‘determine the ultimate merits’” of the case, 

“but rather ‘determine only whether the district court correctly distilled the 

7

In our January 2023 order, we determined that Lindsay’s claim was not moot 

when she withdrew from BSU in October 2020, because she expressed a concrete 

plan to re-enroll and try out for BSU sports teams. Hecox II, 2023 WL 1097255, at 

*1. Lindsay followed through on those plans by re-enrolling at BSU after she 

established Idaho state residency and training to participate in women’s sports 

teams. Id. Indeed, Lindsay planned to try out again for the BSU women’s crosscountry and track teams in Fall 2023, and has been playing for the BSU women’s 

club soccer team since Fall 2022. Id., at *2. Absent the preliminary injunction 

against the Act’s enforcement, Lindsay would be banned from participating on the 

BSU women’s club soccer team. Id. 
16 

applicable rules of law and exercised permissible discretion in applying those rules 

to the facts at hand.’” Saravia for A.H. v. Sessions, 905 F.3d 1137, 1141–42 (9th 

Cir. 2018) (quoting Fyock v. Sunnyvale, 779 F.3d 991, 995 (9th Cir. 2015)). 

However, we will reverse a grant of the preliminary injunction if the district court 

“based its decision . . . on clearly erroneous findings of fact.” Does 1-5 v. 

Chandler, 83 F.3d 1150, 1552 (9th Cir. 1996). 

We review the scope of a preliminary injunction for an abuse of discretion. 

California v. Azar, 911 F.3d 558, 567 (9th Cir. 2018). 

III. PRELIMINARY INJUNCTION

“A preliminary injunction is ‘an extraordinary and drastic remedy, one that 

should not be granted unless the movant, by a clear showing, carries the burden of 

persuasion.’” Lopez v. Brewer, 680 F.3d 1068, 1072 (9th Cir. 2012) (quoting 

Mazurek v. Armstrong, 520 U.S. 968, 972 (1997)). “A plaintiff seeking a 

preliminary injunction must establish that he is likely to succeed on the merits, that 

he is likely to suffer irreparable harm in the absence of preliminary relief, that the 

balance of equities tips in his favor, and that an injunction is in the public interest.” 

Winter v. Nat. Res. Def. Council, Inc., 555 U.S. 7, 20 (2008). The last two factors 

“merge when the Government is the opposing party.” Nken v. Holder, 556 U.S. 

418, 435 (2009).

A. Likelihood of Success on the Merits
17 

The primary issue presented by this appeal is whether the district court 

abused its discretion in concluding that Lindsay was likely to succeed on the merits 

of her equal protection challenge. The Fourteenth Amendment provides that “[n]o 

State shall . . . deny to any person within its jurisdiction the equal protection of the 

laws.” U.S. Const. amend. XIV, § 1. In other words, “all persons similarly 

situated should be treated alike.” City of Cleburne v. Cleburne Living Ctr., 473 

U.S. 432, 439 (1985). The state may not discriminate against classes of people in 

an “arbitrary or irrational” way or with the “bare . . . desire to harm a politically 

unpopular group.” Id. at 446–47. 

When considering an equal protection claim, we determine what level of 

scrutiny applies to a classification under a law or policy, and then decide whether 

the policy at issue survives that level of scrutiny. Our “general rule is that 

legislation is presumed to be valid and will be sustained if the classification drawn 

by the statute is rationally related to a legitimate state interest,” id. at 440, 

otherwise known as rational basis review. However, as gender classifications 

“generally provide[] no sensible ground for differential treatment,” id., “‘all 

gender-based classifications today’ warrant ‘heightened scrutiny.’” VMI, 518 U.S. 

at 555 (quoting J.E.B. v. Alabama ex rel. T.B., 511 U.S. 127, 136 (1994)). Under 

heightened scrutiny, “a party seeking to uphold government action based on sex 
18 

must establish an ‘exceedingly persuasive justification’ for the classification.” Id. 

at 524 (quoting Mississippi Univ. for Women v. Hogan, 458 U.S. 718, 724 (1982)). 

1. Heightened scrutiny applies.

The district court did not err in concluding that heightened scrutiny applies 

because the Act discriminates against transgender women by categorically 

excluding them from female sports, as well as on the basis of sex by subjecting all 

participants in female athletics, but no participants in male athletics, to invasive 

sex verification procedures to implement that policy. Appellants contend that the 

Act classifies based only on sex, not “transgender status,” and permissibly 

excludes “biological males” from female sports under our precedent. See, e.g.,

Clark ex rel. Clark v. Arizona Interscholastic Ass’n (Clark I), 695 F.2d 1126, 

1131–32 (9th Cir. 1982) (holding that excluding boys from a girls’ high school 

volleyball team was permissible to redress past discrimination against women 

athletes and to promote equal opportunity for women). We conclude that while the 

Act certainly classifies on the basis of sex, it also classifies based on transgender 

status, triggering heightened scrutiny on both grounds. 

a. The Act discriminates based on transgender status.

Appellants argue that the Act does not discriminate based on transgender 

status because “[t]he distinction and statutory classification is based entirely on 

[biological] sex, not gender identity.” They assert that the Act’s definition of 
19 

“biological sex” describes only the “physiological differences between the sexes 

relevant to athletics.” But the Act explicitly references transgender women, as did 

its legislative proponents, and its text, structure, findings, and effect all 

demonstrate that the purpose of the Act was to categorically ban transgender 

women and girls from public school sports teams that correspond with their gender 

identity. 

A discriminatory purpose is shown when “the decisionmaker, in this case a 

state legislature, selected or reaffirmed a particular course of action at least in part 

‘because of,’ not merely ‘in spite of,’ its adverse effects upon an identifiable 

group.” Pers. Adm’r of Massachusetts v. Feeney, 442 U.S. 256, 279 (1979). Here,

the district court found that “the law is directed at excluding women and girls who

are transgender, rather than on promoting sex equality and opportunities for 

women.” Hecox I, 479 F. Supp. 3d at 983. This finding is not clearly erroneous. 

Section 33-6202 straightforwardly sets forth the “legislative findings and 

purpose” of the Act, and makes clear that its animating purpose was to ban 

transgender women from “biologically female” teams. These findings explicitly 

discuss transgender women athletes by stating that “a man [sic] who identifies as a 

woman and is taking cross-sex hormones ‘ha[s] an absolute advantage’ over 

female athletes,” and noting that “[t]he benefit[] that natural testosterone provides 
20 

to male athletes is not diminished through the use of puberty blockers and crosssex hormones.” Idaho Code § 33-6202(11). 

During the legislative debate on H.B. 500, the Act’s supporters stated 

repeatedly that the Act’s purpose was to ban transgender women athletes from 

participating on female athletic teams in Idaho. Representative Ehardt, who 

introduced the bill, characterized the law as a “preemptive” strike that would allow 

Idaho to “remove [transgender women] and replace them with the young gal that 

should have been on the team.” Representative Ehardt reiterated that the Act 

would require transgender women to “compete on the side of those biological boys 

and men with whom they look or, about whom they look alike.” Much of the 

legislative debate centered around two transgender women athletes running track 

in Connecticut high schools, as well as one running college track in Montana, and 

the potential “threat” those athletes presented to female athletes in Idaho. When 

Idaho’s then-Attorney General Wasden expressed concerns about the Act’s 

constitutionality, he expressly described it as “targeted toward transgender and 

intersex athletes.” 

The plain language of section 33-6203 bans transgender women from 

“biologically female” teams. The Act divides sports teams into three categories 

based on biological sex: “(a) Males, men, or boys; (b) Females, women, or girls; or 

(c) Coed or mixed.” Id. § 33-6203(1). Sports designated for “females, women, or 
21 

girls” are not open to students of the male sex. Id. § 33-6203(2). And the methods 

for “verify[ing] the student’s biological sex” are restricted to “reproductive 

anatomy, genetic makeup, or normal endogenously produced testosterone levels.” 

Id. § 33-6203(3). However, most gender-affirming medical care for transgender 

females, especially minors, will not or cannot alter the characteristics described in 

the only three verification methods prescribed by the Act, thus effectively banning 

transgender females from female sports.8 As the district court determined, “the 

overwhelming majority of women who are transgender have XY chromosomes,” 

which indicate the male sex, and transgender women cannot change that genetic 

makeup when they transition. Hecox I, 479 F. Supp. 3d at 984. Similarly, as 

medical expert Dr. Deanna Adkins opined, many transgender women and girls do 

not undergo gender-affirming genital surgery to alter their external “reproductive 

anatomy,” often because they cannot afford it or it is inappropriate for their 

individual needs. 

Further, because surgery cannot change transgender women’s internal 

reproductive anatomy by creating ovaries, Dr. Adkins testified that transgender 

women “typically continue to need estrogen therapy” even after surgery and can 

8

In 2023, Idaho adopted legislation prohibiting minors from receiving genderaffirming medical care. See Idaho Code § 18-1506C, enjoined by Poe ex rel. Poe v. 

Labrador, 2023 WL 8935065, at *2 (D. Idaho Dec. 26, 2023), injunction modified 

in part sub nom. by Labrador v. Poe ex rel. Poe, 144 S. Ct. 921 (2024).
22 

never alter their “endogenously produced”—or naturally produced—testosterone 

levels. By contrast, the Act does not allow sex to be verified by a transgender 

woman’s levels of circulating testosterone, which can be altered through medical 

treatment. A transgender woman like Lindsay, for example, can lower her 

circulating testosterone levels through hormone therapy to conform to elite athletic 

regulatory guidelines, but cannot currently alter the endogenous testosterone that 

her body naturally produces. Yet the district court found and the record before it 

supports that circulating testosterone is the “one [sex-related] factor that a 

consensus of the medical community appears to agree” actually affects athletic 

performance. Id. 

Appellants suggest that “biological sex” is a neutral and well-established 

medical and legal concept, rather than one designed precisely by the Idaho 

legislature to exclude transgender and intersex people.9 But the Act’s definition of 

9

In supplemental briefing, Appellants also argue that the Supreme Court’s recent 

decisions in Dobbs v. Jackson Women’s Health Organization, 597 U.S. 215

(2022), and New York State Rifle & Pistol Ass’n v. Bruen, 597 U.S. 1 (2022), “are 

fatal to Hecox’s claim” because the ratifiers of the Fourteenth Amendment would 

have understood “male” to correspond to the definition of “biological male” 

written into the Act. We fail to see how Dobbs, a substantive due process decision 

about whether the federal Constitution protects a woman’s right to obtain an 

abortion, and Bruen, a Second Amendment decision about gun rights, are relevant 

to an equal protection claim based on sex discrimination, unless Appellants are 

suggesting that the Framers would have understood the term “biological sex” by 

reference to reproductive anatomy, genetic makeup, or normal endogenously 

produced testosterone levels. Indeed, the ratifiers of the Fourteenth Amendment 

would certainly not have understood the Act’s definition of “biological sex.” For 
23 

“biological sex” is likely an oversimplification of the complicated biological 

reality of sex and gender. As Dr. Joshua Safer, Executive Director of the Center 

for Transgender Medicine and Surgery at Mount Sinai, explained in his 

declaration, citing the Endocrine Society Guidelines: 

The phrase “biological sex” is an imprecise term that can cause 

confusion. A person’s sex encompasses the sum of several biological 

attributes, including sex chromosomes, certain genes, gonads, sex 

hormone levels, internal and external genitalia, other secondary sex 

example, the drafters of the Fourteenth Amendment would have had no concept of 

what “endogenously produced testosterone levels” meant in 1868, because 

testosterone was not named and isolated as a hormone until 1935. See John M. 

Tomlinson, The Testosterone Story, Trends in Urology & Men’s Health 34, 35 

(2012). Similarly, the ratifiers would not have understood how “genetic makeup” 

influences sex, as chromosomes were first discovered by Walther Flemming in 

1882. D.W. Rudge, The Man Who Invented the Chromosome, 97 Heredity 136, 

136 (2006) (reviewing Oren Harman, The Man Who Invented the Chromosome: A 

Life of Cyril Darlington (2004)). 

Moreover, there is evidence that transgender people have existed since 

ancient times. See generally Lauren Talalay, The Gendered Sea: Iconography, 

Gender, and Mediterranean Prehistory, in THE ARCHEOLOGY OF MEDITERRANEAN 

PREHISTORY 130–33 (Emma Blake & A. Bernard Knapp eds., 2005). Appellants

appear to argue that because transgender people were marginalized in 1868, they 

should be afforded no constitutional protections on the basis of their transgender 

status. But this argument would undermine decades of Supreme Court precedent 

striking down laws that discriminate on the basis of sex. See Reed v. Reed, 404 

U.S. 71, 76 (1971) (holding that an Idaho statute that preferenced men as 

administrators of estates “ma[d]e the very kind of arbitrary legislative choice 

forbidden by the Equal Protection Clause of the Fourteenth Amendment”); 

Frontiero v. Richardson, 411 U.S. 677, 687 (1973) (“[S]tatutory distinctions 

between the sexes often have the effect of invidiously relegating the entire class of 

females to inferior legal status without regard to the actual capabilities of its 

individual members.”); see also Weinberger v. Weisenfeld, 420 U.S. 636, 645

(1975); Craig v. Boren, 429 U.S. 190, 210 (1976); Duren v. Missouri, 439 U.S. 

357, 360 (1979); VMI, 518 U.S. at 519.
24 

characteristics, and gender identity. These attributes are not always 

aligned in the same direction.

Indeed, two percent of all babies are born “intersex,” or with “a wide range of 

natural variations in physical traits—including external genitals, internal sex 

organs, chromosomes, and hormones—that do not fit typical binary notions of 

male and female bodies.” Br. of Amici Curiae InterACT at 3–4. Intersex people 

who identify as women are equally banned under the Act from playing on Idaho 

women’s teams. And while scientists are not fully certain why some people 

identify as transgender, it appears likely that there is some biological 

explanation—such as gestational exposure to elevated levels of testosterone—that 

causes certain individuals to identify as a different gender than the one assigned to 

them at birth. See AAP Br. at 14. 

Finally, the Act’s discriminatory purpose is further evidenced by the Act’s 

prohibition of “biological males” from female-designated teams because that 

prohibition affects one group of athletes only—transgender women. See Crawford

v. Board of Education, 458 U.S. 527, 544 (1982) (explaining that the 

“disproportionate effect of official action provides an important starting point” for 

determining whether a “[discriminatory] purpose was [its] motivating factor” 

(internal quotation marks omitted)). Before the Act’s passage, both the IHSAA 

and the NCAA prohibited cisgender men and boys from participating on femaledesignated sports teams. Both associations also had policies that allowed 
25 

transgender women and girls to participate on female athletic teams after 

completing one year of hormone therapy to suppress testosterone levels. Giving 

effect to the Act still prohibits men and boys from participating on female athletic 

teams. But all transgender girls and women, even those who were previously 

eligible consistent with the IHSAA and NCAA policies, are now barred from 

female athletics. The Act’s only contribution to Idaho’s student-athletic landscape 

is to entirely exclude transgender women and girls from participating on female 

sports teams. And where a statute’s “undisputed purpose [] and only effect . . . is 

to exclude transgender girls . . . from participation on girls sports teams,” that 

statute discriminates on the basis of transgender status. B.P.J. ex rel. Jackson v. W.

Va. State Bd. of Educ., 98 F.4th 542, 556 (4th Cir. 2024).

In addition to having a discriminatory purpose and effect, the Act is also 

facially discriminatory against transgender female athletes. We have previously 

rejected an argument like that Appellants raise here—that because section 33-6203 

uses “biological sex” in place of the word “transgender,” it is not targeted at 

excluding transgender girls and women. In Latta v. Otter, 771 F.3d 456 (9th Cir. 

2014), we held that Idaho and Nevada laws that banned same-sex marriage facially 

discriminated on the basis of sexual orientation, even though the laws did so by 

classifying couples based on “procreative capacity” instead of sexual orientation. 

Id. at 467–68. We explained:
26 

Effectively if not explicitly, [defendants] assert that while these laws 

may disadvantage same-sex couples and their children, heightened 

scrutiny is not appropriate because differential treatment by sexual 

orientation is an incidental effect of, but not the reason for, those laws. 

However, the laws at issue distinguish on their face between oppositesex couples, who are permitted to marry and whose out-of-state 

marriages are recognized, and same-sex couples, who are not permitted 

to marry and whose marriages are not recognized. Whether facial 

discrimination exists “does not depend on why” a policy discriminates, 

“but rather on the explicit terms of the discrimination.” Hence, while 

the procreative capacity distinction that defendants seek to draw could 

represent a justification for the discrimination worked by the laws, it 

cannot overcome the inescapable conclusion that Idaho and Nevada do 

discriminate on the basis of sexual orientation. 

Id. at 467–68 (quoting Int’l Union, United Auto., Aerospace & Agr. Implement 

Workers of Am., UAW v. Johnson Controls, Inc., 499 U.S. 187, 199 (1991)). Here, 

the Act’s use of “biological sex” functions as a form of “[p]roxy discrimination.” 

Pac. Shores Props., LLC v. City of Newport Beach, 730 F.3d 1142, 1160 n.23 (9th 

Cir. 2013). The definition of “biological sex” in the Act is written with “seemingly 

neutral criteria that are so closely associated with the disfavored group that 

discrimination on the basis of such criteria is, constructively, facial discrimination 

against the disfavored group.” Id.; see also Lawrence v. Texas, 539 U.S. 558, 575 

(2003) (“When homosexual conduct is made criminal by the law of the State, that 

declaration in and of itself is an invitation to subject homosexual persons to 

discrimination . . . .”). The Act’s specific classification of “biological sex” has 

similarly been carefully drawn to target transgender women and girls, even if it 

does not use the word “transgender” in the definition. 
27 

Adams ex rel. Kasper v. School Board of St. Johns County, 57 F.4th 791 

(11th Cir. 2022) (en banc), upon which Appellants rely to support their argument 

that the Act does not discriminate against transgender girls or women, is 

inapposite. There, the Eleventh Circuit upheld a lower court order rejecting an 

equal protection challenge to a K-12 school policy that provided female, male, and 

sex-neutral bathrooms and required male students to use the male-designated 

bathrooms, required female students to use the female bathrooms, and 

accommodated transgender students with the sex-neutral bathrooms. See id. at 

797. The policy defined “male” and “female” as the gender identified on a 

student’s birth certificate. See id. The Eleventh Circuit rejected the argument that 

the policy unconstitutionally discriminated on the basis of transgender status 

because it was “substantially related” to the school district’s important interest in 

securing its pupils’ privacy and welfare and was not targeted at transgender 

students—at most, it had a disparate impact upon them which did not rise to the 

level of a constitutional violation because no animus was shown. See id. at 811. 

Importantly, in Adams—as opposed to here—there was “no [record] evidence 

suggesting that the School Board enacted the [] policy because of . . . its adverse 

effects upon transgender students.” Id. at 810 (second alteration in original) 

(internal quotation marks omitted). To the contrary, the school district in Adams
28 

had studied the issues raised by the LGBTQ community and had also enacted 

policies that affirmatively accommodated transgender students.10 

Appellants likewise misrely on a footnote in Geduldig v. Aiello, 417 U.S. 

484 (1974), for the proposition that a legislative classification based on biological 

sex is not a classification based on transgender status. See id. at 496 n.20. In 

Geduldig, the Supreme Court stated that a classification based on pregnancy is not 

per se a classification based on sex, even though “it is true that only women can 

become pregnant.” Id. However, the Court held that “distinctions involving 

pregnancy” that are “mere pretexts designed to effect an invidious discrimination”

are subject to heightened scrutiny. Id. Here, it appears that the definition of 

“biological sex” was designed precisely as a pretext to exclude transgender women 

from women’s athletics—a classification that Geduldig prohibits. 

Finally, Appellants contend that the Act does not discriminate based on 

transgender status because the “Act does not prohibit biologically female athletes 

who identify as male from competing on male sports teams consistent with their 

gender identity.” But a law is not immune to an equal protection challenge if it 

discriminates only against some members of a protected class but not others. See, 

e.g., Rice v. Cayetano, 528 U.S. 495, 516–17 (2000) (“Simply because a class . . . 

10 Although Adams is plainly distinguishable, we express no view on the merits of 

the decision. 
29 

does not include all members of [a] race does not suffice to make the classification 

race neutral.”); Nyquist v. Mauclet, 432 U.S. 1, 7–9 (1977) (holding that singling 

out some but not all undocumented immigrants for discrimination constituted a 

“classification based on alienage”); Mathews v. Lucas, 427 U.S. 495, 504 n.11 

(1976) (“That the statutory classifications challenged here discriminate among 

illegitimate children does not mean, of course, that they are not also properly 

described as discriminating between legitimate and illegitimate children.”). 

b. Heightened scrutiny applies because the Act discriminates on the basis of 

transgender status. 

We have previously held that heightened scrutiny applies to laws that 

discriminate on the basis of transgender status, reasoning that gender identity is at 

least a “quasi-suspect class.” Karnoski v. Trump, 926 F.3d 1180, 1200–01 (9th 

Cir. 2019).

In Karnoski, we reviewed an injunction against the implementation of a 

2017 Presidential Memorandum and Departments of Defense and Homeland 

Security policies that effectively precluded transgender individuals from serving in 

the U.S. military. Id. at 1189. The district court had applied strict scrutiny in 

enjoining the policy, while the government argued that the policy should be 

reviewed under a rational basis standard. Id. at 1200. We held that because the 

implementing policy “on its face treats transgender persons differently than other 

persons . . . something more than rational basis but less than strict scrutiny 
30 

applies.” Id. at 1201. We therefore adopted the heightened scrutiny approach of 

VMI and Witt v. Department of Air Force, 527 F.3d 806, 818 (9th Cir. 2008), to 

review the military’s ban on transgender persons who experienced gender 

dysphoria or who have undergone gender transition.11 Id. We are thus compelled 

to review the constitutionality of the Act under heightened scrutiny as it classifies 

based on transgender status. 

Moreover, discrimination on the basis of transgender status is a form of sexbased discrimination. It is well-established that sex-based classifications are 

subject to heightened scrutiny. See VMI, 518 U.S. at 533–34. The Supreme Court 

recently held in the Title VII context that “it is impossible to discriminate against a 

person for being . . . transgender without discriminating against that individual 

based on sex.” Bostock v. Clayton County, 590 U.S. 644, 660 (2020).12 Indeed, 

11 The Supreme Court determined in VMI that for “cases of official classification 

based on gender” a reviewing court must apply a “heightened review standard” and 

determine whether the state has demonstrated an “exceedingly persuasive 

justification” for the classification. 518 U.S. at 533–34. In Witt, we applied a 

“heightened scrutiny” approach to the military’s “Don’t Ask, Don’t Tell” policy 

for gay and lesbian servicemembers, determining that “when the government 

attempts to intrude upon the personal and private lives of homosexuals . . . the 

government must advance an important governmental interest, the intrusion must 

significantly further that interest, and the intrusion must be necessary to further that 

interest.” 527 F.3d at 819. 

12 See also Nondiscrimination on the Basis of Sex in Education Programs or 

Activities Receiving Federal Financial Assistance, 87 Fed. Reg. 41,390, 41,571 

(Aug. 1, 2024) (to be codified at 34 C.F.R. pt. 106) (clarifying that “discrimination 

on the basis of sex” under Title IX includes discrimination based on “sex 

stereotypes, sex characteristics . . . and gender identity”).
31 

“[m]any courts . . . have held that various forms of discrimination against 

transgender individuals constitute sex-based discrimination for purposes of the 

Equal Protection Clause because such policies punish transgender persons for 

gender non-conformity, thereby relying on sex stereotypes.” Grimm v. Gloucester 

Cnty. Sch. Bd., 972 F.3d 586, 608 (4th Cir. 2020) (applying heightened scrutiny to 

a bathroom policy); see also Whitaker ex rel. Whitaker v. Kenosha Unified Sch. 

Dist. No. 1 Bd. of Educ., 858 F.3d 1034, 1051 (7th Cir. 2017), abrogated on other 

grounds, Illinois Republican Party v. Pritzker, 972 F.3d 760 (7th Cir. 2020) 

(same); Brandt ex rel. Brandt v. Rutledge, 47 F.4th 661, 670–71 & n.4 (8th Cir. 

2022) (applying heightened scrutiny to affirm a preliminary injunction against a 

law that prohibited “gender transition procedures” because the law discriminated 

on the basis of sex); Eknes-Tucker v. Marshall, 603 F. Supp. 3d 1131, 1147 (M.D. 

Ala. 2022) (applying heightened scrutiny to a law that prohibited various medical 

treatments for gender dysphoria in minors).13 

c. Heightened scrutiny applies because the Act discriminates against all 

participants in female sports. 

13 Both Idaho and the Intervenors note that the Eleventh Circuit expressed “grave 

doubt” in a footnote in Adams that transgender people constitute a “quasi-suspect 

class.” Adams, 57 F.4th at 803 n.5 (internal quotation marks omitted). This 

dictum is unpersuasive, as the Eleventh Circuit declined to decide the issue or 

further opine on its “doubt.” In any event, as a three-judge panel we cannot 

overrule the binding precedent of our circuit. See Miller v. Gammie, 335 F.3d 889, 

899 (9th Cir. 2003). 
32 

In addition to discriminating on the basis of transgender status, the Act 

discriminates on the basis of sex, because only students who participate on female 

designated sports teams, and not students who participate on male designated 

sports teams, are subject to the sex dispute verification process. The Act expressly 

states that only “[a]thletic teams or sports designated for females, women, or girls 

shall not be open to students of the male sex.” Idaho Code § 33-6203(2). The Act 

does not ban “biological females” from “teams or sports designated for males.” 

Therefore, transgender and cisgender men who compete on male-designated teams 

are not subject to the sex dispute verification process. The sex dispute verification 

process simply does not apply to male designated sports teams. 

The Act thus classifies on the basis of sex by subjecting only participants in 

women’s and girls’ sports, whether cisgender or transgender, to the risk and 

humiliation of having their sex “disputed” and then suffering intrusive medical 

testing as a prerequisite for participation on school sports teams. And where 

women’s and girls’ sports are subject to separate requirements for educational 

opportunities that are “unequal in tangible and intangible” ways from those for 

men, those requirements are tested under heightened scrutiny. VMI, 518 U.S. at 

547. 

2. The Act likely does not survive heightened scrutiny. 
33 

The district court correctly concluded that the Act likely does not survive 

heightened scrutiny. Heightened scrutiny is a “demanding” standard, with the 

burden “rest[ing] entirely on the State” to demonstrate an “exceedingly persuasive” 

justification for its differential treatment. VMI, 518 U.S. at 533. To survive 

heightened scrutiny, the government must demonstrate “that the [challenged] 

classification serves important governmental objectives and that the discriminatory 

means employed are substantially related to the achievement of those objectives.” 

Id. at 516 (alteration in original) (internal quotation marks and citations omitted). 

Our review under heightened scrutiny is an extremely fact-bound test, requiring us 

to “examine [a policy’s] actual purposes and carefully consider the resulting 

inequality to ensure our most fundamental institutions neither send nor reinforce 

messages of stigma or second-class status.” SmithKline Beecham Corp. v. Abbott 

Labs., 740 F.3d 471, 483 (9th Cir. 2014). 

Appellants contend that, “[d]ue to the average physiological differences” 

between men and women, the Act substantially advances the important state 

interest of “promot[ing] sex equality . . . by providing opportunities for female 

athletes to demonstrate their skill, strength, and athletic abilities [and] 

opportunities to obtain recognition and accolades, college scholarships, and the 

numerous other long-term benefits that flow from success in athletic endeavors.” 

Idaho Code § 33-6202(12). We have previously held that furthering women’s 
34 

equality and promoting fairness in female athletic teams is an important state 

interest. Clark I, 695 F.2d at 1131. However, on the record before us, the district 

court correctly determined that the Act’s means—categorically banning 

transgender women and girls from all female athletic teams and subjecting all 

participants in female athletics to intrusive sex verification procedures—likely are 

not substantially related to, and in fact undermine, those asserted objectives. 

a. Clark I and Clark II do not control the outcome of Lindsay’s claim. 

Our decisions in Clark I and Clark ex rel. Clark v. Arizona Interscholastic 

Ass’n (Clark II), 886 F.2d 1191 (9th Cir. 1989), are inapposite. In Clark I and 

Clark II, we held that public high schools could constitutionally prohibit cisgender 

male student athletes from participation on women’s teams in order to further the 

important government interest of “redressing past discrimination against women in 

athletics and promoting equality of opportunity between the sexes.” Clark I, 695 

F.2d at 1131. 

Specifically in Clark I, we held that an Arizona Interscholastic Association 

policy that separated high school volleyball teams by gender and prohibited boys 

from playing on girls’ teams did not violate the Equal Protection Clause. Clark I, 

695 F.2d at 1127. There, Clark wished to play on the girls’ volleyball team 

because his particular high school did not offer boys’ volleyball teams. Id. We 

first recognized that, in applying heightened scrutiny, “the Supreme Court is 
35 

willing to take into account actual differences between the sexes, including 

physical ones.” Id. at 1229 (citing Michael M. v. Sonoma Cnty. Superior Ct., 450 

U.S. 464, 468–69 (1981) (upholding a statutory rape statute that held only males 

culpable because only women can become pregnant, thus furthering the 

government’s interest in preventing teen pregnancy)). We concluded that general 

gender separation in school sports was substantially related to the government’s 

interest in women’s equality in athletics. Id. at 1131. We reasoned that “due to 

average physiological differences, males would displace females to a substantial 

extent if they were allowed to compete for positions on the volleyball team.” Id. 

Thus, if men were allowed to compete on the women’s teams, women’s overall 

athletic opportunities would decrease, while men’s overall athletic opportunities 

would remain greater than women’s. 

Eight years later, in Clark II, the original Clark I plaintiff’s brother brought a 

second “mystifying” action challenging the same policy, arguing that the state 

“ha[d] been wholly deficient in its efforts to overcome the effects of past 

discrimination against women in interscholastic athletics, and that this failure 

vitiate[d] its justification for a girls-only volleyball team.” Clark II, 886 F.2d at 

1193. Applying Clark I, we affirmed that the gender classification for Arizona 

school sports was constitutional. Id. at 1194. 
36 

Appellants argue that “[t]he only difference between Hecox and the Clark 

brothers is gender identity,” which does not change the physiological advantages 

that “biological males” have over cisgender women. But this is a false assumption. 

First, Lindsay takes medically prescribed hormone therapy to suppress her 

testosterone and raise her estrogen levels. This treatment has lowered her 

circulating testosterone levels—which impact athletic prowess and have slowed 

her racing times by at least “five to ten percent”—and her testosterone levels were 

“well below the levels required to meet NCAA eligibility for cross country and 

track” in Fall 2022, as the district court found. See Hecox I, 479 F. Supp. 3d at 

946. Lindsay’s treatment has dramatically altered her bodily systems and 

secondary sex characteristics. As the district court found, “it is not clear that 

transgender women who suppress their testosterone have significant physiological 

advantages over cisgender women,” unlike the cisgender boys at issue in Clark I 

and Clark II. Id. at 978. The record in Clark I made clear that sex was a valid 

proxy for average physiological differences between men and women. Here, by 

contrast, the district court found that the ban on transgender female athletes applies 

broadly to many students who do not have athletic advantages over cisgender 

female athletes. Thus, a faithful application of Clark I supports, rather than 

undermines, the district court’s reasoning here.
37 

Second, as the district court noted, transgender women, “like women 

generally . . . have historically been discriminated against, not favored.” Id. at 977. 

A recent study by the CDC concluded that “transgender students reported 

significantly higher incidents of being bullied, feeling unsafe traveling to or from 

school, being threatened with a weapon at school, and being made to engage in 

unwanted sexual relations.” Br. of Amici Curiae GLBTQ Legal Advocates & 

Defenders and the National Center for Lesbian Rights, at 9; see also Whitaker, 858 

F.3d at 1051 (“There is no denying that transgender individuals face 

discrimination, harassment, and violence because of their gender identity.”). 

Unlike the policy in Clark I, the Act perpetuates historic discrimination against 

both cisgender and transgender women by categorically excluding transgender 

women from athletic competition and subjecting all participants in women’s 

athletics to an invasive sex dispute verification process. 

Moreover, the district court correctly found that “under the Act, women and 

girls who are transgender will not be able to participate in any school sports, unlike 

the boys in Clark I, who generally had equal [or greater] athletic opportunities.” 

Hecox I, 479 F. Supp. 3d at 977. Here, unlike in Clark I, transgender women are 

not being denied one “particular opportunity” to participate on women’s teams 

even though their “overall opportunity is not inferior” to that of women. Clark I, 

695 F.2d at 1126. As a practical matter, the Act bars transgender women and girls 
38 

in Idaho from all participation in student athletics—under its explicit terms, they 

cannot play on teams that conform to their transgender status. The argument 

advanced by Representative Ehardt that the Act does not discriminate against 

transgender women because they can still play on men’s teams is akin to the 

argument we rejected in Latta, that same-sex marriage bans do not discriminate 

against gay men because they are free to marry someone of the opposite sex. See 

Latta, 771 F.3d at 467 (holding unconstitutional two marriage bans that 

“distinguish on their face between opposite-sex couples who are permitted to 

marry and whose out-of-state marriages are recognized, and same-sex couples, 

who are not permitted to marry and whose marriages are not recognized”). As 

medical expert Dr. Jack Turban stated, “forcing [transgender students] to play on a 

sports team that does not match their gender identity would damage their mental 

health” by “forcing them to express themselves as cisgender.” Lindsay declared 

that she would never compete on a men’s team, as it would be “embarrassing and 

painful to be forced onto a team for men—like constantly wearing a big sign that 

says ‘this person is not a “real” woman.’” 

The district court also found that, on the record before it, “transgender 

women have not and could not ‘displace’ cisgender women in athletics ‘to a 

substantial extent.’” Hecox I, 479 F. Supp. 3d at 977 (quoting Clark I, 695 F.2d at 

1131). Appellants misrely on a single line from Clark II to argue that the 
39 

participation of just one transgender woman on a team risks displacing any 

individual cisgender woman: “If males are permitted to displace females on the 

school volleyball team even to the extent of one player like Clark, the goal of equal 

participation by females in interscholastic athletics is set back, not advanced.” 

Clark II, 886 F.2d at 1193. This statement, however, was made in response to the 

argument in Clark II that because sex separation had not fully met Arizona’s goal 

of equality of participation in sports, Arizona no longer had an important interest in 

the policy. We did not think Clark’s proposed remedy for the inequality of 

opportunities for female athletes—allowing him to play on the girls’ teams—

would advance the “goal of equal participation by females in interscholastic 

sports.” Id. Because transgender women represent about 0.6 percent of the 

general population, the district court did not err in finding it unlikely that they 

would displace cisgender women from women’s sports. 

The only issue we decided in Clark—whether a sex-based classification was 

constitutionally permissible—is not in dispute here. Lindsay does not challenge 

the exclusion of cisgender males from female-designated sports. The question that 

is presented here—whether a classification based on transgender status is 

constitutionally permissible—is one that was not presented or discussed in Clark.

b. The Act is likely not substantially related to an important government 

interest.
40 

Nor did the district court err in concluding that the Act likely fails 

heightened scrutiny because it is not substantially related to its stated goals of 

equal participation and opportunities for women athletes. The district court 

concluded that the Act’s categorical ban does not advance its asserted objectives 

based on three factual findings, none of which is “illogical, implausible, or without 

support in inferences that may be drawn from the facts in the record.” Pom 

Wonderful LLC v. Hubbard, 775 F.3d 1118, 1123 (9th Cir. 2014) (citation 

omitted). Moreover, the Act’s sweeping prohibition on transgender female athletes 

in Idaho—encompassing all students, regardless of whether they have gone 

through puberty or hormone therapy, without any evidence of transgender athletes 

displacing female athletes in Idaho, and enforced through a mechanism that 

subjects all participants in female athletics to the threat of an invasive physical 

examination—is likely too unrelated to the State’s legitimate objectives to satisfy 

heightened scrutiny. 

First, the district court found that there was scientifically “no evidence to 

suggest a categorical bar against a transgender female athlete’s participation in 

sports is required in order to promote ‘sex equality’ or to ‘protect athletic 

opportunities for females’ in Idaho.” Hecox I, 479 F. Supp. 3d at 978–79. 

Appellants argue that the district court misread the available medical evidence, 

which they contend demonstrates that endogenous testosterone levels give 
41 

“biological males” a permanent athletic advantage over cisgender women. 

However, the district court did not clearly err by relying upon the testimony of a 

medical expert, Dr. Safer, who testified that there was a medical consensus that the 

“primary known driver of differences in athletic performance between elite male 

athletes and elite female athletes” is “the difference in [circulating] testosterone” 

levels, as opposed to “endogenously produced” testosterone levels, and “[a] 

person’s genetic make-up and internal and external reproductive anatomy are not 

useful indicators of athletic performance and have not been used in elite 

competition for decades.” The district court reasonably credited Dr. Safer’s 

opinion that a transgender woman who received hormone therapy to lower her 

circulating levels of testosterone would likely not have “physiological 

characteristics” that would lead to enhanced athletic prowess when compared to a 

cisgender woman. 

Appellants presented contrary medical testimony by Dr. Gregory Brown that 

hormone therapy suppression did not eliminate all of the physiological advantages 

that an individual experiences through male puberty. However, as the district court 

found, Dr. Brown’s opinion was not supported by the studies he relied upon, 

because the majority of the studies he cited discussed the average differences 

between male and female athletes in general, not the difference between 

transgender and cisgender women athletes. And one study that he cited—the 
42 

Handelsman study—actually came to the opposite conclusion, concluding that 

“evidence makes it highly likely that the sex difference in circulating testosterone

of adults explains most, if not all, of the sex differences in sporting performance.” 

The studies that the Idaho legislature relied upon to conclude that the 

benefits of “natural testosterone” could not be diminished through hormone 

therapy were likewise flawed. For example, one of the studies was altered after 

peer review to remove its conclusions regarding transgender athletes, and, as Idaho 

concedes, that “study and its findings were not based specifically on transgender 

athletes.” The legislature also relied on a study by Professor Coleman, who 

personally urged Governor Little to veto the bill because the legislature had 

misinterpreted her work. 

Moreover, as the district court found, the Act sweeps much more broadly 

than simply excluding transgender women who have gone through “endogenous 

puberty.” The Act’s categorical ban includes transgender students who are young 

girls in elementary school or even kindergarten. Other transgender women take 

puberty blockers and never experience endogenous puberty, yet the Act 

indiscriminately bars them from participation in women’s student athletics, 

regardless of their testosterone levels. Although the scientific understanding of 

transgender women’s potential physiological advantage is fast-evolving and 

somewhat inconclusive, we are limited to reviewing the record before the district 
43 

court. And the record in this case does not ineluctably lead to the conclusion that 

all transgender women, including those like Lindsay who receive hormone therapy, 

have a physiological advantage over cisgender women. 

Second, as the district court found, there was very little anecdotal evidence 

at the time of the Act’s passage that transgender women had displaced or were 

displacing cisgender women in sports or scholarships or like opportunities. In 

2020, both the IOC and the NCAA required transgender women to suppress their 

testosterone for only a year for eligibility to compete on women’s teams.14 The 

record before the district court includes anecdotal evidence of only four 

transgender athletes who had ever competed in cisgender women’s sports, 

14 Although today the IOC and NCAA policies evaluate eligibility for transgender 

participation in athletics on a sport-by-sport basis, neither policy endorses the 

categorical exclusion of transgender women. They instead favor an “evidencebased approach” with “no presumption of advantage.” Int’l Olympics Comm., 

IOC Framework on Fairness, Inclusion and Non-Discrimination on the Basis of 

Gender Identity and Sex Variations 4 (2021), 

https://stillmed.olympics.com/media/Documents/Beyond-the-Games/HumanRights/IOC-Framework-Fairness-Inclusion-Non-discrimination-2021.pdf#page=4

(last visited June 6, 2023); see also Nat’l Collegiate Athletics Ass’n, Transgender 

Student-Athlete Participation Policy (April 17, 2023), 

https://www.ncaa.org/sports/2022/1/27/transgender-participation-policy.aspx (last 

visited May 24, 2023). And while the World Athletics Council, the international 

governing body for track and field, recently adopted a more stringent policy of 

categorically excluding post-pubescent transgender women from elite athletic 

competitions, its policy does not bar transgender women who have not experienced 

endogenous puberty from eligibility. See Press Release, World Athletics Counsel, 

World Athletics Council Decides on Russia, Belarus, and Female Eligibility (Mar. 

23, 2023), https://worldathletics.org/news/press-releases/council-meeting-march2023-russia-belarus-female-eligibility (last visited May 24, 2023).
44 

including two high school runners who competed in Connecticut and were 

subsequently defeated by cisgender women in competition. While the Intervenors 

state they were defeated by a transgender athlete, June Eastwood, in a running 

competition at the University of Montana, Eastwood eventually lost to a different 

cisgender athlete in that same competition. Lindsay’s own athletic career belies 

the contention that transgender women who have undergone male puberty have an 

absolute advantage over cisgender women: she has never qualified for BSU’s track 

team despite trying out. 

There is likewise no evidence in the record of a transgender woman 

receiving an athletic scholarship over a cisgender woman in Idaho. Moreover, as 

the district court noted, the Act’s broad sweep—banning transgender women’s 

participation not just in high school and college athletics, but elementary school 

and club sports—“belies any genuine concern with an impact on athletic 

scholarships,” which are relevant to only a small portion of the competitive teams 

encompassed by the Act. Hecox I, 479 F. Supp. 3d at 983.

Of course, when applying heightened scrutiny, we “must accord substantial 

deference to the predictive judgments” of legislative bodies. Turner Broad. Sys., 

Inc. v. FCC, 512 U.S. 622, 665 (1994). But this does not “insulate[]” predictive 

judgments “from meaningful judicial review altogether.” Id. at 666. 

“[U]nsupported legislative conclusions as to whether particular policies will have 
45 

societal effects of the sort at issue in this case—determinations which often, as 

here, implicate constitutional rights—have not been afforded deference by the 

[Supreme] Court.” Latta, 771 F.3d at 469; see also Lopez-Valenzuela v. Arpaio, 

770 F.3d 772, 784 (9th Cir. 2014) (en banc) (“[T]he absence of any credible 

showing that the [challenged law] addressed a particularly acute problem” was 

“quite relevant” to a showing that the law did not survive heightened scrutiny.). A 

vague, unsubstantiated concern that transgender women might one day dominate 

women’s athletics is insufficient to satisfy heightened scrutiny. 

Third, the district court questioned the Act’s true objectives, finding that 

Idaho’s interest was not in “promoting sex equality” but in “excluding transgender 

women and girls from women’s sports entirely.” Hecox I, 479 F. Supp. 3d at 983. 

Before the Act’s passage, the existing NCAA and Idaho state rules governed 

transgender women’s participation as measured by circulating testosterone levels, 

and there was no record evidence that transgender women and girls threatened to 

dominate female student athletics. The record indicates that Idaho may have 

wished “to convey a message of disfavor” toward transgender women and girls, 

who are a minority in this country. See Latta, 771 F.3d at 476. And “[t]his is a 
46 

message that Idaho . . . simply may not send” through unjustifiable 

discrimination.15 Id. at 476.

Further evidencing the lack of means-ends fit between the categorical ban of 

transgender female athletes and the Legislature’s purported purpose of promoting 

athletic equality is the Act’s overly broad enforcement mechanism: the sex dispute 

verification provision, which is integral to the Act’s operation.

16

 Under the Act, 

15 The Fourth Circuit recently held that West Virginia’s categorical ban could not 

be applied to “prevent a 13-year-old transgender girl who takes puberty blocking 

medication and has publicly identified as a girl since the third grade from 

participating in her school’s cross country and track teams.” B.P.J. by Jackson v. 

W. Va. State Bd. of Educ., 98 F.4th 542, 550 (4th Cir. 2024). Other federal and 

state courts have similarly enjoined transgender sports bans, and no categorical ban 

has yet been upheld on appeal. See Doe v. Horne, No. 23-16026 (9th Cir.) 

(pending appeal challenging the preliminary injunction against Arizona’s statute 

regulating transgender female athlete participation); A.M. by E.M. v. Indianapolis 

Pub. Sch., 617 F. Supp. 3d 950, 969 (S.D. Ind. July 26, 2022), appeal dismissed, 

No. 22-2332, 2023 WL 371646, at *1 (7th Cir. Jan. 19, 2023) (granting a 

preliminary injunction against transgender participation in athletics under Title 

IX); Roe v. Utah High Sch. Activities Ass’n, No. 220903262, 2022 WL 3907182, at 

*1 (Utah Dist. Ct. Aug. 19, 2022) (granting a preliminary injunction against a 

categorical ban under the Utah Constitution’s equivalent of an equal protection 

clause); see also Barrett v. Montana, No. DV-21-581B, at *5–7 (Mont. Dist. Ct. 

Sept. 14, 2022) (granting summary judgment against a categorical ban on the 

ground that only Montana public university officials have the authority to regulate 

athletic competition in public universities). 

16 In its petition for rehearing en banc, Idaho argues that Lindsay lacks Article III 

standing to challenge the dispute and sex verification procedures. Pet. Reh’g En 

Banc at 2, 15–16. We need not address this argument because we do not consider 

whether the dispute and sex verification procedures constitute an independent 

equal protection violation; we address only whether Lindsay is likely to succeed on 

her equal protection challenge to the transgender ban as a whole. Furthermore, to 

the extent Idaho challenges Lindsay’s standing to challenge section 33-6203(3), we 

reject the argument. Lindsay has standing to challenge section 33-6203(3) because 
47 

anyone—be it a teammate, coach, parent, or a member of an opposing team—may 

“dispute” a player’s “biological sex,” requiring that player to visit her “personal 

health care provider . . . [who will] verify the student’s biological sex” through the 

player’s “reproductive anatomy, genetic makeup, or normal endogenously 

produced testosterone levels.” Idaho Code § 33-6203(3). The Act’s express terms 

limit the verification procedure to a “routine sports physical examination” by 

“relying only on one (1) or more of the following: the student’s reproductive 

anatomy, genetic makeup, or normal endogenously produced testosterone levels.” 

Id. (emphasis added). By its plain text, the Act provides that a student’s sex can be 

verified exclusively by these three enumerated methods. Thus, the district court 

reasonably found incredulous defense counsel’s argument that the Act merely 

required Lindsay to obtain a letter from her doctor stating that Lindsay “is female.” 

Hecox I, 479 F. Supp. 3d at 964 & n.19, 983. If that was all that was required to 

verify a student’s sex under the Act, Lindsay could simply obtain such a statement 

and the Act (and this appeal) would be rendered meaningless. 

Any one of the three exclusive procedures requires far more than a “routine 

sports physical” exam or simply asking whether a patient is female or not. As 

it is an integral part of the transgender ban that she indisputably has standing to 

challenge—it supplies “the Act’s definition of ‘biological sex.’” Hecox I, 479 F. 

Supp. 3d at 984. 
48 

Lindsay’s medical expert Dr. Sara Swobada described, analyzing a student’s 

“genetic makeup” would require referral to a “pediatric endocrinologist” who 

would conduct a “chromosomal microarray” that would reveal a “range of genetic 

conditions” beyond sex chromosomes. Hormone testing would also require an 

“pediatric endocrinologist,” and is not a “routine part of any medical evaluation.” 

Of course, the expense and burden of these tests would be borne only by the 

students who play female athletics and their families. 

Requiring a student to find a medical practitioner to examine their 

reproductive anatomy, which is what a typical gynecological exam entails, is 

unconscionably invasive, with the potential to traumatize young girls and women. 

As Dr. Swobada opined, examining a female patient’s “reproductive anatomy” 

would necessitate inspecting a student athlete’s genitalia and conducting a pelvic 

examination or transvaginal ultrasound to determine whether that student has 

ovaries. She further explained that pelvic examinations for young patients are 

generally not required for minors, including adolescents, and are only conducted 

when medically necessary “with sedation and appropriate comfort measures to 

limit psychological trauma.” Yet the Act’s sex verification process subjects girls 

as young as elementary schoolers to unnecessary gynecological examinations 

merely because an individual “disputes” their sex. 
49 

The psychological burden of these searches falls not only on transgender 

women like Lindsay but also on all women and girls who play female athletics. As 

amici describe, “[s]ex verification procedures have a long, checkered history in 

female sports that continue to this day.” Br. of Amici Curiae National Women’s 

Law Center, et al. at 15. In the 1960s, the IOC would force female athletes to strip 

and parade in front of a panel of doctors to prove that they were, in fact, women. 

Id. The process was discontinued after a public outcry. Id. One intersex athlete 

who failed a sex verification procedure described being “so ‘tormented’ and 

‘unbearably embarrassed’ that ‘she attempted suicide’ by ‘swallowing poison.’” 

Id. at 17 (quoting Ruth Padawer, The Humiliating Practice of Sex-Testing Female 

Athletes, N.Y. Times Magazine (June 28, 2016)). Tellingly, while many athletic 

organizations have tightened their rules for transgender women’s competition since 

2020, none appears to have instituted a process that required gynecological 

examinations or invasive physical examinations.17 Of the twenty-four other states 

that have passed restrictions on transgender women’s participation in women’s 

sports, none has authorized a similar sex verification process.18 Idaho has not 

17 The IOC has expressly disavowed invasive sex verification procedures, stating 

that “[c]riteria to determine eligibility for a gender category should not include 

gynecological examinations or similar forms of invasive physical examinations, 

aimed at determining an athlete’s sex, sex variations or gender.” See Int’l Olympic 

Comm., supra, at 5. 

18 Most states that have instituted categorical bans on transgender participation in 

student athletics have verified sex via a student’s birth certificate. Oklahoma and 
50 

offered any “exceedingly persuasive justification” warranting the imposition of this 

objectively degrading and disturbing process on young women and girls who 

participate in female athletics. 

We must “reject measures that classify unnecessarily and overbroadly by 

gender when more accurate and impartial lines can be drawn.” Sessions v. 

Morales-Santana, 137 582 U.S. 47, 63 n.13 (2017). While the Act purports to 

further athletic opportunities for Idaho’s female students, the district court 

correctly concluded that the Act does not further this goal, and in fact “appears 

unrelated to the interests the Act purportedly advances.” Hecox I, 470 F. Supp. 3d 

at 979. And “[i]ntentional discrimination on the basis of gender by state action 

violates the Equal Protection Clause[] where, as here, the discrimination serves to 

ratify and perpetuate invidious, archaic, and overbroad stereotypes.” J.E.B. v. 

Alabama ex rel. T.B., 511 U.S. 127, 131 (1994). Thus, we need not and do not 

decide what policy would justify the exclusion of transgender women and girls 

from Idaho athletics under the Equal Protection Clause, because the profound lack 

of means-end fit here demonstrates that the Act likely does not survive heightened 

scrutiny. 

B. Irreparable Harm

Kentucky require a student or a student’s parent or legal guardian submit sworn 

affidavits to confirm their “biological sex.” See Okla. Stat. Ann. tit. 70, § 27-

106(D); Ky. Rev. Stat. Ann. § 164.2813(2). 
51 

The district court properly concluded that Lindsay faced irreparable harm 

absent an injunction. “It is well established that the deprivation of constitutional 

rights unquestionably constitutes irreparable injury.” Hernandez v. Sessions, 872 

F.3d 976, 994 (9th Cir. 2017) (internal quotation marks and citation omitted). 

Therefore, as the Act is likely unconstitutional, “it follows inexorably . . . that 

[Hecox] ha[s] [] carried [her] burden as to irreparable harm.” Id. at 995. 

More concretely, if the preliminary injunction is lifted, Lindsay will be 

barred from trying out for or participating on any women’s sports at BSU, 

including the women’s club soccer team, which she joined to improve her running 

skills and experience “the camaraderie of being on a team.” See Idaho Code § 33-

6203(3). Lindsay would also be subject to the threat of the sex dispute verification 

process and unnecessary examinations or medical testing. These are all specific 

“harm[s] for which there is no adequate legal remedy” in the absence of an 

injunction. Ariz. Dream Act Coal. v. Brewer, 757 F.3d 1053, 1068 (9th Cir. 2014). 

C. Balance of the Equities & Public Interest

The district court also did not err in concluding that the balance of the 

equities weighed in favor of a preliminary injunction. The third and fourth 

preliminary injunction factors—assessing the harm to the opposing party and 

weighing the public interest—merge where, as here, the government is the 

opposing party. Nken, 556 U.S. at 435. Here, Lindsay faces deeply personal, 
52 

irreparable harms without injunctive relief, including being barred from all female 

college athletic teams and the prospect of invasive medical testing if her gender is 

“disputed.” 

The preliminary injunction does not appear to inflict any comparable harm 

on the Appellants. Under the pre-Act status quo, the NCAA policies for college 

athletics and the IHSAA policies for high school athletics govern transgender 

female participation in sports, and Idaho schools have complied with those policies 

for over a decade. The district court found no “evidence that transgender women 

threatened equality in sports, girls’ athletic opportunities, or girls’ access to 

scholarships in Idaho” during that decade, and thus Appellants failed to 

demonstrate any harm from issuance of the injunction. Hecox I, 479 F. Supp. 3d at 

988. Moreover, as the district court found, Intervenors themselves may also be 

harmed by the sex dispute verification process, to which they are subject simply by 

virtue of playing sports in Idaho. Because “the public interest and the balance of 

the equities favor preven[ting] the violation of a party’s constitutional rights,” Ariz. 

Dream Act, 757 F.3d at 1060 (alteration in original) (internal quotation marks and 

citation omitted), we affirm that the district court did not abuse its discretion in 

weighing this factor. 

IV. SCOPE OF THE INJUNCTION
53 

Although we agree with the district court that the Act harms “not just the 

constitutional rights of transgender girls and women athletes . . . [but also] the 

constitutional rights of every girl and woman athlete in Idaho,” we remand to the 

district court to clarify the scope of the preliminary injunction. Hecox I, 479 F. 

Supp. 3d at 988. “A district court has considerable discretion in fashioning 

suitable relief and defining the terms of an injunction,” and “[a]ppellate review of 

those terms ‘is correspondingly narrow.’” Lamb-Weston, Inc. v. McCain Foods, 

Ltd., 941 F.2d 970, 974 (9th Cir. 1991) (quoting Coca-Cola Co. v. Overland, Inc., 

692 F.2d 1250, 1256 n.16 (9th Cir.1982)). However, injunctive relief “must be 

tailored to remedy the specific harm alleged,” and “[a]n overbroad injunction is an 

abuse of discretion.” Id. (finding that a worldwide injunction to protect a trade 

secret was not an abuse of discretion). Under Federal Rule of Civil Procedure Rule 

65(d)(1), “[e]very order granting an injunction . . . must: (A) state the reasons why 

it issued; (B) state its terms specifically; and (C) describe in reasonable detail—and 

not by referring to the complaint or other document—the act or acts restrained or 

required.” 

Here, the scope of the injunction is not clear. Although the district court 

granted Plaintiffs’ motion for preliminary injunction, the court’s order does not 

specify whether enforcement of the Act is enjoined in whole or in part, nor does it 

specify whether enforcement of the Act is enjoined facially or as applied to 
54 

particular persons. See Hecox I, 479 F. Supp. 3d at 988. On remand, the district 

court should tailor the injunction to provide the specificity that Rule 65(d)(1) 

requires. 

We do not agree with the Intervenors, however, that the preliminary 

injunction would necessarily be overbroad as a matter of law if it extends to 

nonparties despite the district court’s dismissal of Lindsay’s facial challenge. 

“[A]n injunction ‘should be no more burdensome to the defendant than necessary 

to provide complete relief to the plaintiffs before the court.’” City & County of San 

Francisco v. Barr, 965 F.3d 753, 765 (9th Cir. 2020) (quoting L.A. Haven Hospice, 

Inc. v. Sebelius, 638 F.3d 644, 664 (9th Cir. 2011)). “[B]ut there is ‘no general 

requirement that an injunction affect only the parties in the suit.’” East Bay 

Sanctuary Covenant, 993 F.3d 640, 680 (9th Cir. 2021) (quoting Bresgal v. Brock, 

843 F.2d 1163, 1169–1170 (9th Cir. 1987). Rather, “[t]he equitable relief granted 

by the district court is acceptable where it is necessary to give prevailing parties 

the relief to which they are entitled.” Id. (quotation marks omitted). Before 

deciding whether it can accord Lindsay complete relief without enjoining the Act 

in part or in whole as to all female student athletes in Idaho, the district court 

should consider the effect, if any, of the Supreme Court’s decision in Labrador v. 

Poe, 144 S. Ct. 921 (2024). 

V.
55 

While we address only the Act before us, and opine on no other regulation or 

policy, we must observe that both the science and the regulatory framework 

surrounding issues of transgender women’s participation in female-designated 

sports is rapidly evolving. Since Lindsay filed her initial challenge, the IOC and 

NCAA have adopted more limited policies as to transgender female participation 

in women’s sports, requiring the governing entities for each sport to formulate 

sport-specific policies. Relying on medical evidence, many sports organizations 

have tightened their eligibility criteria for transgender women’s teams, including 

incorporating guidelines for lower testosterone levels for eligibility to compete.19 

The U.S. Department of Education has proposed new Title IX regulations 

addressing restrictions on transgender athletes’ eligibility that would require “such 

criteria” to “be substantially related to the achievement of an important educational 

objective and minimize harms to students whose opportunity to participate on a 

19 See, e.g., USA Swimming, USA Swimming Releases Athlete Inclusion, 

Competitive Equity and Eligibility Policy (Feb. 1, 2022), 

https://tinyurl.com/mr2k4tvp (announcing a policy for USA Swimming that elite 

transgender women athletes must show testosterone levels below 5 nmol/L 

continuously for at least 36 months); Bicycling, The UCI Announces Changes to 

Its Policy on Transgender Athletes (June 17, 2022), 

https://www.bicycling.com/news/a40320907/uci-transgender-policy-2022/ 

(announcing a testosterone limit of 2.5 nmol/L for elite bicyclists (halved from the 

previous 5.0 nmol/L) for a suppression period of 24 months); Olalla Cernuda, 

World Triathlon Executive Board approves Transgender Policy, World Triathlon

(Aug. 3, 2022), https://tinyurl.com/yxw4syzw (requiring below a 2.5 nmol/L 

testosterone level for 24 months for triathletes). 
56 

male or female team consistent with their gender identity would be limited or 

denied.”20 These more narrowly drawn policies, which are not before us, attempt 

to balance transgender inclusion with competitive fairness—a policy question that 

such regulatory bodies are best equipped to address. 

VI. CONCLUSION

We recognize that, after decades of women being denied opportunities to 

meaningfully participate in athletics in this country, many cisgender women 

athletes reasonably fear being shut out of competition because of transgender 

athletes who “retain an insurmountable athletic advantage over cisgender women.” 

See Br. of Amici Curiae Sandra Bucha, et al. at 8. We also recognize that athletic 

participation confers on students not just an opportunity to win championships and 

scholarships, but also the benefits of shared community, teamwork, leadership, and 

discipline. See generally Br. of Amici Curiae 176 Athletes in Women’s Sports 

(describing the benefits of sports, and diversity in women’s sports, on all students). 

Excluding transgender youth from sports necessarily means that some transgender 

youth will be denied those educational benefits. 

20 Nondiscrimination on the Basis of Sex in Education Programs or Activities 

Receiving Federal Financial Assistance: Sex-Related Eligibility Criteria for Male 

and Female Athletic Teams, 88 Fed. Reg. 22860 (proposed April 13, 2023) (to be 

codified at 34 C.F.R. pt. 106).
57 

However, we need not and do not decide the larger question of whether any 

restriction on transgender participation in sports violates equal protection. 

Heightened scrutiny analysis is an extraordinarily fact-bound test, and today we 

simply decide the narrow question of whether the district court, on the record 

before it, abused its discretion in finding that Lindsay was likely to succeed on the 

merits of her equal protection claim. Because it did not, we affirm the district 

court’s order granting preliminary injunctive relief as applied to Lindsay, vacate 

the injunction as applied to non-parties, and remand to the district court to address 

the scope and clarity of the injunction. 

AFFIRMED IN PART; VACATED IN PART; REMANDED.