United States Court of Appeals
FOR THE DISTRICT OF COLUMBIA CIRCUIT

Argued January 25, 2021

Decided August 13, 2021

No. 20-1025
ENVIRONMENTAL HEALTH TRUST, ET AL.,PETITIONERSv.
FEDERAL COMMUNICATIONS COMMISSION AND UNITEDSTATES OF AMERICA,RESPONDENTS

Consolidated with 20-1138
On Petitions for Review of an Orderof the Federal Communications Commission
W. Scott McCollough argued the cause for petitioners.
With him on the joint briefs were Edward B. Myers and Robert
F. Kennedy, Jr.
Sharon Buccino was on the brief for amici curiae Natural
Resources Defense Council and Local Elected Officials insupport of petitioners.

2
Dan Kleiber and Catherine Kleiber, pro se, were on thebrief for amici curiae Dan and Catherine Kleiber in support ofpeititioners.
James S. Turner was on the brief for amicus curiae
Building Biology Institute in support of petitioners.
Stephen L. Goodman was on the brief for amicus curiae
Joseph Sandri in support of petitioners.
Ashley S. Boizelle, Deputy General Counsel, Federal
Communications Commission, argued the cause forrespondents. With her on the brief were Jonathan D.
Brightbill, Principal Deputy Assistant Attorney General at thetime the brief was filed, U.S. Department of Justice, Eric
Grant, Deputy Assistant Attorney General at the time the brief
was filed, Jeffrey Beelaert and Justin Heminger, Attorneys,
Thomas M. Johnson, Jr., General Counsel at the time the brief
was filed, Federal Communications Commission, Jacob M.
Lewis, Associate General Counsel, and William J. Scher and
Rachel Proctor May, Counsel. Richard K. Welch, Deputy
Associate General Counsel, entered an appearance.
Before: HENDERSON, MILLETT and WILKINS, Circuit
Judges.
Opinion for the Court filed by Circuit Judge WILKINS.
Opinion dissenting in part filed by Circuit Judge
HENDERSON.
WILKINS, Circuit Judge: Environmental Health Trust andseveral other groups and individuals petition for review of anorder of the Federal Communications Commission (“theCommission”) terminating a notice of inquiry regarding the3adequacy of the Commission’s guidelines for exposure toradiofrequency radiation. The notice of inquiry requested
comment on whether the Commission should initiate arulemaking to modify its guidelines. The Commission
concluded that no rulemaking was necessary. Petitioners argue
that the Commission violated the requirements of the
Administrative Procedure Act by failing to respond to
significant comments. Petitioners also argue that the National
Environmental Policy Act required the Commission to issue anenvironmental assessment or environmental impact statement
regarding its decision to terminate its notice of inquiry.
We grant the petitions in part and remand to theCommission. The Commission failed to provide a reasoned
explanation for its determination that its guidelines adequately
protect against the harmful effects of exposure toradiofrequency radiation unrelated to cancer.
I.
The Federal Communications Commission regulates
various facilities and devices that transmit radio waves andmicrowaves, including cell phones and facilities for radio, TV,and cell phone communications. 47 U.S.C. §§ 301, 302a(a);see EMR Network v. FCC, 391 F.3d 269, 271 (D.C. Cir. 2004).
Radio waves and microwaves are forms of electromagnetic
energy that are collectively described by the term“radiofrequency” (“RF”). Office of Eng’g & Tech., Fed.
Commc’ns Comm’n, OET Bulletin No. 56, Questions andAnswers about Biological Effects and Potential Hazards ofRadiofrequency Electromagnetic Fields 1 (4th ed. Aug. 1999).
The phenomenon of radio waves and microwaves moving
through space is described as “RF radiation.” Id.
We often associate the term “radiation” with the term“radioactivity.” “Radioactivity,” however, refers only to the4emission of radiation with enough energy to strip electrons
from atoms. Id. at 5. That kind of radiation is called “ionizing
radiation.” Id. It can produce molecular changes and damage
biological tissue and DNA. Id. Fortunately, RF radiation is“non-ionizing,” meaning that it is not sufficiently energetic tostrip electrons from atoms. Id. It can, however, heat certain
kinds of materials, like food in your microwave oven or, atsufficiently high levels, human body tissue. Id. at 6–7.
Biological effects that result from the heating of body tissue by
RF energy are referred to as “thermal” effects, and are known
to be harmful. Id. Exposure to lower levels of RF radiation
might also cause other, “non-thermal” biological effects. Id. at
8. Whether it does, and whether such effects are harmful, aresubjects of debate. Id.
The National Environmental Policy Act (“NEPA”) and its
implementing regulations require federal agencies to “establish
procedures to account for the environmental effects of [their]
proposed actions.” Am. Bird Conservancy, Inc. v. FCC, 516
F.3d 1027, 1032 (D.C. Cir. 2008) (per curiam). If an agency
proposes a “major Federal action[]” that stands to“significantly affect[] the quality of the human environment,”
the agency must prepare an environmental impact statement(“EIS”) that examines the adverse environmental effects of the
proposed action and potential alternatives. 42 U.S.C. §4332(C). Not every agency action, however, requires the
preparation of a full EIS. Theodore Roosevelt Conservation
P’ship v. Salazar, 616 F.3d 497, 503 (D.C. Cir. 2010). If it isunclear whether a proposed action will “significantly affect[]the quality of the human environment,” 42 U.S.C. § 4332(C),the responsible agency may prepare a more limited
environmental assessment (“EA”). See 40 C.F.R. § 1501.5(a).
An EA serves to “[b]riefly provide sufficient evidence andanalysis for determining whether to prepare an [EIS] or afinding of no significant impact.” 40 C.F.R. § 1501.5(c)(1).

5
Additionally, an agency may use “categorical exclusions” to“define categories of actions that normally do not have asignificant effect on the human environment and therefore do
not require preparation of an environmental impact statement.”
40 C.F.R. § 1500.4(a); see also 40 C.F.R. § 1501.4(a).
To fulfill its obligations under NEPA, the Commission has
promulgated guidelines for human exposure to RF radiation.
Cellular Phone Taskforce v. FCC, 205 F.3d 82, 87 (2d Cir.
2000). The guidelines set limits for RF exposure. Before theCommission authorizes the construction or use of any wirelessfacility or device, the applicant for authorization must
determine whether the facility or device is likely to expose
people to RF radiation in excess of the limits set by theguidelines. 47 C.F.R. § 1.1307(b). If the answer is yes, theapplicant must prepare an EA regarding the likely effects of theCommission’s authorization of the facility or device. Id.
Depending on the contents of the EA, the Commission may
require the preparation of an EIS, and may subject approval of
the application to a full vote by the Commission. Office ofEng’g & Tech., Fed. Commc’ns Comm’n, OET Bulletin No.
65, Evaluating Compliance with FCC Guidelines for Human
Exposure to Radiofrequency Electromagnetic Fields 6 (ed. 9701, Aug. 1997). If the answer is no, the applicant is generally
not required to prepare an EA. 47 C.F.R. § 1.1306(a).
The Commission last updated its limits for RF exposure in
1996. Resolution of Notice of Inquiry, Second Report andOrder, Notice of Proposed Rulemaking, and Memorandum
Opinion and Order, 34 FCC Rcd. 11,687, 11,689–90 (2019)(“2019 Order”); see also Telecommunications Act of 1996,
Pub. L. No. 104-104, § 704(b), 110 Stat. 56, 152 (directing theCommission to “prescribe and make effective rules regarding
the environmental effects of radio frequency emissions” within
180 days). The limits are based on standards for RF exposure

6issued by the American National Standards InstituteCommittee (“ANSI”), the Institute of Electrical and Electronic
Engineers, Inc. (“IEEE”), and the National Council on
Radiation Protection and Measurements (“NCRP”). In re
Guidelines for Evaluating the Environmental Effects ofRadiofrequency Radiation, 11 FCC Rcd. 15,123, 15,134–35,
15,146–47 (1996). The limits are designed to protect against“thermal effects” of exposure to RF radiation, but not “nonthermal” effects. EMR Network, 391 F.3d at 271.
In March 2013, the Commission issued a notice of inquiry
regarding the adequacy of its 1996 guidelines.
See
Reassessment of Radiofrequency Exposure Limits & Policies,
Notice of Inquiry, 28 FCC Rcd. 3,498 (2013) (“2013 Notice ofInquiry”). The Commission divided its notice of inquiry into
five sections. In the first section, it sought comment on the
propriety of its exposure limits for RF radiation, particularly as
they relate to device use by children. Id. at 3,575–80. In thesecond section, the Commission sought comment on how tobetter provide information to consumers and the public about
exposure to RF radiation and methods for reducing exposure.
Id. at 3,580–82. In the third section, the Commission soughtcomment on whether it should impose additional precautionary
restrictions on devices and facilities that are unlikely to expose
people to RF radiation in excess of the limits set by theCommission’s guidelines. Id. at 3,582–85. In the fourth andfifth sections, the Commission sought comment on whether itshould change its methods for determining whether devices andfacilities comply with the Commission’s guidelines. Id. at
3,585–89.
The Commission explained that it was issuing the noticeof inquiry in response to changes in the ubiquity of wirelessdevices and in scientific standards and research since 1996. Id.
at 3,570. Specifically, the Commission noted that the IEEE had

7“published a major revision to its RF exposure standard in2006.” Id. at 3,572. The Commission also noted that theInternational Commission on Non-Ionizing Radiation
Protection had published RF exposure guidelines in 1998 thatdiffered somewhat from the Commission’s 1996 guidelines,
and was likely to release a revision of those guidelines “in thenear future.” Id. at 3,573. And the Commission noted that theInternational Agency for Research on Cancer (“IARC”) had
classified RF radiation as possibly carcinogenic to humans, andwas likely to release a detailed monograph regarding thatclassification prior to the resolution of the notice of inquiry. Id.
at 3,575 & n.385. The Commission invited public comment on
all of these developments, but underscored that it would “workclosely with and rely heavily—but not exclusively—on theguidance of other federal agencies with expertise in the healthfield.” Id. at 3,571.
In December 2019, the Commission issued a final orderresolving its 2013 notice of inquiry by declining to undertake
any of the changes contemplated in the notice of inquiry. See
2019 Order, 34 FCC Rcd. at 11,692–97.
In January 2020, Petitioners Environmental Health Trust,Consumers for Safe Cell Phones, Elizabeth Barris, andTheodora Scarato timely petitioned this Court for review of theCommission’s 2019 final order. In February 2020, Petitioners
Children’s Health Defense, Michele Hertz, Petra Brokken, Dr.
David O. Carpenter, Dr. Paul Dart, Dr. Toril H. Jelter, Dr. Ann
Lee, Virginia Farver, Jennifer Baran, and Paul Stanley, M.Ed.,
timely petitioned the Ninth Circuit for review of the sameorder, and the Ninth Circuit transferred their petition to thisCourt pursuant to 28 U.S.C. § 2112. This Court consolidated
the petitions. We have jurisdiction under 47 U.S.C. § 402(a)and 28 U.S.C. § 2342(1).

8II.
Petitioners challenge the 2019 final order under NEPA andthe Administrative Procedure Act (“APA”). We begin with the
APA.
A.
Petitioners argue that the order is arbitrary and capricious
and therefore must be set aside under 5 U.S.C. § 706(2)(A) for
the following reasons: (1) the order fails to acknowledge
evidence of negative health effects caused by exposure to RF
radiation at levels below the limits set by the Commission’s
1996 guidelines, including evidence of cancer, radiation
sickness, and adverse effects on sleep, memory, learning,
perception, motor abilities, prenatal and reproductive health,and children’s health; (2) the order fails to respond tocomments concerning environmental harm caused by RFradiation; (3) the order fails to discuss the implications of longterm exposure to RF radiation, exposure to RF pulsation or
modulation (two methods of imbuing radio waves withinformation), and the implications of technologicaldevelopments that have occurred since 1996, including theubiquity of wireless devices and Wi-Fi, and the emergence of“5G” technology; (4) the order fails to adequately explain theCommission’s refusal to modify its procedures for determining
whether cell phones comply with its RF limits; and (5) theorder fails to respond to various “additional legal
considerations,” Pet’rs’ Br. at 84.
Before discussing these arguments, and the Commission’s
responses to them, we clarify our standard of review. The
arbitrary and capricious standard of the Administrative
Procedure Act “encompasses a range of levels of deference tothe agency.” Am. Horse Prot. Ass’n v. Lyng, 812 F.2d 1, 4
(D.C. Cir. 1987). We completely agree with the dissenting

9opinion that the Commission’s order is entitled to a high degreeof deference, both because it is akin to a refusal to initiate arulemaking, see id. at 4–5, and because it concerns highly
technical determinations of the kind courts are ill-equipped tosecond-guess, see Am. Radio Relay League, Inc., v. FCC, 524
F.3d 227, 233 (D.C. Cir. 2008). So as to the governing law, thedissenting opinion and we are on the same page. Nevertheless,
the Commission’s decision to terminate its notice of inquiry
must be “reasoned” if it is to survive arbitrary and capricious
review. See Am. Horse, 812 F.2d at 5; Am. Radio, 524 F.3d at
241. As with other agency decisions not to engage inrulemaking, we will overturn the Commission’s decision if
there is “compelling cause, such as plain error of law or afundamental change in the factual premises previously
considered by the agency[.]” Flyers Rights Educ. Fund, Inc. v.
Fed. Aviation Admin., 864 F.3d 738, 743 (D.C. Cir. 2017)(quoting WildEarth Guardians v. EPA, 751 F.3d 649, 653(D.C. Cir. 2014)). When an agency in the Commission’s
position is confronted with evidence that its current regulations
are inadequate or the factual premises underlying its priorjudgment have eroded, it must offer more to justify its decision
to retain its regulations than mere conclusory statements. See
Am. Horse, 812 F.2d at 6; Am. Radio, 524 F.3d at 241. Rather,
the agency must provide “assurance that [it] considered therelevant factors,” and it must provide analysis that follows “adiscernable path to which the court may defer.” Am. Radio,
524 F.3d at 241.
i.
Under this highly deferential standard of review, we findthe Commission’s order arbitrary and capricious in its failure
to respond to record evidence that exposure to RF radiation atlevels below the Commission’s current limits may cause
negative health effects unrelated to cancer. (As we explain

10
below, we find that the Commission offered an adequate
explanation for its determination that exposure to RF radiation
at levels below the Commission’s current limits does not cause
cancer.)That failure undermines the Commission’s
conclusions regarding the adequacy of its testing procedures,
particularly as they relate to children, and its conclusions
regarding the implications of long-term exposure to RF
radiation, exposure to RF pulsation or modulation, and theimplications of technological developments that have occurredsince 1996, all of which depend on the premise that exposure
to RF radiation at levels below its current limits causes nonegative health effects.
Accordingly, we find thoseconclusions arbitrary and capricious as well. Finally, we findthe Commission’s order arbitrary and capricious in its complete
failure to respond to comments concerning environmental
harm caused by RF radiation.
Petitioners point to multiple studies and reports, whichwere published after 1996 and are in the administrative record,
purporting to show that RF radiation at levels below theCommission’s current limits causes negative health effects
unrelated to cancer, such as reproductive problems andneurological problems that span from effects on memory to
motor abilities. See, e.g., J.A. 3,068 (BIOINITIATIVE WORKINGGROUP, BIOINITIATIVE REPORT (Cindy Sage & David O.
Carpenter eds., 2012) (describing evidence that human sperm
and their DNA are damaged by low levels of RF radiation));
J.A. 5,243 (Igor Yakymenko et al., Oxidative Mechanisms ofBiological Activity of Low-Intensity Radiofrequency Radiation,
ELECTROMAGNETIC BIOLOGY & MED., EARLY ONLINE, 1–16
(2015)); J.A. 5,259–69 (Henrietta Nittby et al., Increased
Blood-Brain Barrier Permeability in Mammalian Brian 7 Days
After Exposure to the Radiation from a GSM-900 Mobile
Phone, 16 PATHOPHYSIOLOGY 103 (2009)); J.A. 5,320–68(Henry Lai, A Summary of Recent Literature on

11
Neurobiological Effects of Radiofrequency Radiation, in
MOBILE COMMUNICATIONS AND PUBLIC HEALTH 187–222 (M.
Markov ed., 2018)); J.A. 5,994–6,007 (Milena Foerster et al.,A Prospective Cohort Study of Adolescents’ Memory
Performance and Individual Brain Dose of Microwave
Radiation from Wireless Communication, 126 ENV’T HEALTHPERSPS. 077007 (July 2018)). Petitioners also point toapproximately 200 comments submitted by individuals who
advised the Commission that either they or their family
members suffer from radiation sickness, “a constellation of
mainly neurological symptoms that manifest as a result of RF[]
exposure.” Pet’rs’ Br. at 30–31, 30 n.99.
The Commission argues that its order adequately
responded to this evidence by citing the Food and Drug
Administration (“FDA”)’s determination that exposure to RF
radiation at levels below the Commission’s current limits does
not cause negative health effects. The order cites threestatements from the FDA. First, the order cites an FDA
webpage titled “Do cell phones pose a health hazard?” that, asof December 4, 2017, stated that “[t]he weight of scientificevidence has not linked cell phones with any health problems.”
2019 Order, 34 FCC Rcd. at 11,692–93, 11,693 n.31. Second,the order cites a February 2018 statement from the Director of
the FDA’s Center for Devices and Radiological Healthadvising the public that
As part of our commitment to protecting the
public health, the FDA has reviewed, and willcontinue to review, many sources of scientificand medical evidence related to the possibilityof adverse health effects from radiofrequency
energy exposure in both humans and animals
and will continue to do so as new scientific data
are published. Based on our ongoing evaluation

12of the issue, the totality of the available
scientific evidence continues to not support
adverse health effects in humans caused byexposures at or under the current
radiofrequency energy exposure limits.
Id. at 11,695 n.42. Third, the order cites an April 2019 letterfrom the Director of the FDA’s Center for Devices andRadiological Health that does not discuss non-cancer-related
health effects but instead addresses a 2018 study by the
National Toxicology Program that found that exposure to RF
radiation emitted by cell phones may cause cancer in rodents.
2019 Order, 34 FCC Rcd. at 11,692 & n.28. The letter explainsthat “[a]s a part of our ongoing monitoring activities, we havereviewed the results and conclusions of the recently publishedrodent study from the National Toxicology Program in thecontext of all available scientific information, including
epidemiological studies, and concluded that no changes to thecurrent standards are warranted at this time.” Letter fromJeffrey Shuren, M.D., J.D., Dir., Ctr. for Devices &Radiological Health, Food & Drug Admin., Dep’t of Health &Hum. Servs., to Julius Knapp, Chief, Off. Of Eng’g & Tech.,
FCC (April 24, 2019).
We do not agree that these statements provide a reasoned
explanation for the Commission’s decision to terminate its
notice of inquiry. Rather, we find them to be of the conclusory
variety that we have previously rejected as insufficient tosustain an agency’s refusal to initiate a rulemaking. In
American Horse, this Court considered whether the Secretaryof Agriculture had offered a satisfactory explanation under the
APA of his refusal to institute rulemaking proceedings
regarding the practice of deliberately injuring show horses byfastening heavy chains or similar equipment—referred to as“action devices”—to the horses’ front limbs. 812 F.2d at 2. In13
response to the argument that a certain study presented facts
that merited a new rulemaking, the Secretary offered thefollowing two-sentence explanation:
6. I have reviewed studies and other materials,
relating to action devices, presented by humane
groups, Walking Horse industry groups, andindependent institutions, including the study
referred to in the Complaint.
7. On the basis of this information, I believe thatthe most effective method of enforcing the Act
is to continue the current regulations.
Id. at 5. This Court found these “two conclusory sentences . . .
insufficient to assure a reviewing court that the agency’s
refusal to act was the product of reasoned decisionmaking.” Id.
at 6. American Horse explained that the study at issue “may or
may not remove a ‘significant factual predicate’ of the original
rules’ gaps[,]” and remanded to the Secretary to make that
determination. Id. at 7.
Similarly, in American Radio, this Court considered
whether the Commission had offered a satisfactory explanation
for its decision to retain in its regulations a particular“extrapolation factor”—an estimate of the projected rate at
which radio frequency strength decreases from a radiationemitting source—despite studies submitted in a petition forreconsideration indicating that a different extrapolation factor
would be more appropriate. 524 F.3d at 240–41. The
Commission explained its decision by asserting that “[n]o new
information has been submitted that would provide aconvincing argument for modifying the extrapolation factor . .
. at this time.” Id. (internal alterations omitted). We rejectedthat explanation as conclusory and unreasoned. Id.

14
The statements from the FDA on which the Commission’sorder relies are practically identical to the Secretary’s statementin American Horse and the Commission’s statement in
American Radio. They explain that the FDA has reviewed
certain information—here, “all,” “the weight,” or “the totality”
of “scientific evidence.” And they state the FDA’s conclusion
that, in light of that information, exposure to RF radiation atlevels below the Commission’s current limits does not cause
harmful health effects. But they offer “no articulation of thefactual . . . bases” for the FDA’s conclusion. Am. Horse, 812
F.2d at 6 (internal quotation marks omitted). In other words,
they do not explain why the FDA determined, despite thestudies and comments that Petitioners cite, that exposure to RF
radiation at levels below the Commission’s current limits does
not cause harmful health effects. Such conclusory statements“cannot substitute for a reasoned explanation,” for they provide“neither assurance that the [FDA] considered the relevant
factors nor [do they reveal] a discernable path to which thecourt may defer.” Am. Radio, 524 F.3d at 241. They instead
represent a failure by the FDA to address the implication of
Petitioners’ studies: The factual premise—the non-existenceof non-thermal biological effects—underlying the current RF
guidelines may no longer be accurate.
When repeated by the Commission, the FDA’s
conclusory statements still do not substitute for the reasoned
explanation that the APA requires. It is the Commission’s
responsibility to regulate radio communications, 47 U.S.C. §301, and devices that emit RF radiation and interfere with radio
communications, id. § 302a(a), and to do so in the public
interest, including in regard to public health, Banzhaf v. FCC,
405 F.2d 1082, 1096 (D.C. Cir. 1968). Even the Commission
itself recognizes this. See 2019 Order, 34 FCC Rcd. at 11,689(“The Commission has the responsibility to set standards for
RF emissions”); 2013 Notice of Inquiry, 28 FCC Rcd. at 3,571

15(explaining that the Commission opened the notice of inquiry“to ensure [it] [was] meeting [its] regulatory responsibilities”
and that it would “work closely with and rely heavily—but not
exclusively—on the guidance of other federal agencies withexpertise in the health field” in order to “fully discharge[] [its]regulatory responsibility”) (emphasis added). And the APA
requires that Commission’s decisions concerning theregulation of radio communications and devices be reasoned.
The Commission’s purported reasoning in this case is that it
chose to rely on the FDA’s evaluation of the studies in therecord. Absent explanation from the FDA as to how and why
it reached its conclusions regarding those studies, however, wehave no basis on which to review the reasonableness of theCommission’s decision to adopt the FDA’s conclusions.
Ultimately, the Commission’s order remains bereft of any
explanation as to why, in light of the studies in the record, itsguidelines remain adequate. The Commission may turn to the
FDA to provide such an explanation, but if the FDA fails to doso, as it did in this case, the Commission must turn elsewhereor provide its own explanation. Were the APA to require less,our very deferential review would become nothing more than arubber stamp.
The Commission also argues that its order provided areasoned explanation for its decision to terminate the notice ofinquiry, despite Petitioners’ evidence, by observing that “noexpert health agency expressed concern about theCommission’s RF exposure limits,” and that “no evidence has
moved our sister health and safety agencies to issue substantive
policy recommendations for strengthening RF exposure
regulation.” 2019 Order, 34 FCC Rcd. at 11,692. The silenceof other expert agencies, however, does not constitute a
reasoned explanation for the Commission’s decision toterminate its notice of inquiry for the same reason that the
FDA’s conclusory statements do not constitute a reasoned

16
explanation: silence does not indicate why the expert agencies
determined, in light of evidence suggesting to the contrary, that
exposure to RF radiation at levels below the Commission’s
current limits does not cause negative health effects unrelated
to cancer. Silence does not even indicate whether the expert
agencies made any such determination, or whether they
considered any of the evidence in the record.
Our decision in EMR Network is not to the contrary.
There, we rejected the argument that the Commission
improperly delegated its NEPA duties by relying on input fromother government agencies and non-governmental expert
organizations in deciding whether to initiate a rulemaking tomodify its RF radiation guidelines. 391 F.3d at 273. We found
the Commission “not to have abdicated its responsibilities, butrather to have properly credited outside experts,” and noted that“the FCC’s decision not to leap in, at a time when the EPA (andother agencies) saw no compelling case for action, appears to
represent the sort of priority-setting in the use of agency
resources that is least subject to second-guessing by courts.”
Id. (citing Am. Horse, 812 F.2d at 4). We agree with thedissenting opinion that the Commission may credit outside
experts in deciding whether to initiate a rulemaking to modify
its RF radiation guidelines. To be sure, “[a]gencies can be
expected to respect the views of such other agencies as to those
problems for which those other agencies are more directly
responsible and more competent.” City of Boston Delegationv. FERC, 897 F.3d 241, 255 (D.C. Cir. 2018) (internal
alteration and quotation marks omitted).
What theCommission may not do, however, is rely on an outside
expert’s silence or conclusory statements in lieu of somereasoned explanation for its decision. And while it is certainly
true that an agency’s decision not to initiate a rulemaking at atime when other agencies see no compelling case for action
may represent “the sort of priority-setting in the use of agency

17
resources that is least subject to second-guessing by courts,”
EMR Network, 391 F.3d at 273, the same is true of most agency
decisions not to initiate a rulemaking, see Am. Horse, 812 F.2d
at 4–5. Nevertheless, an agency’s decision not to initiate arulemaking must have some reasoned basis, and an agency
cannot simply ignore evidence suggesting that a major factual
predicate of its position may no longer be accurate. Id. at 5.
Nor does Cellular Phone Taskforce help the Commission.
There, the Second Circuit rejected the argument that theCommission was required to consult with the Environmental
Protection Agency (“EPA”) or other outside agencies before
declining to modify its RF radiation guidelines in the face of
new evidence regarding non-thermal effects caused by RFradiation. 205 F.3d at 90–91. In so holding, the Second Circuit
found that “[i]t was fully reasonable for the FCC to expect theagency with primacy in evaluating environmental impacts tomonitor all relevant scientific input into the FCC’s
reconsideration, particularly because the EPA had been
assigned the lead role in RF radiation health effects since1970,” and that the Commission was not required to “supply
the new evidence to the other federal agencies with expertisein the area.” Id. at 91. But the Second Circuit did not hold that
the Commission could rely solely on the silence or unexplained
conclusions of other federal agencies to justify its own inaction.
It merely held that the Commission was not required to consult
with outside agencies before declining to modify its RF
radiation guidelines. No party before us today questions the
propriety of that holding.
Finally, the Commission argues that the Commission itself
addressed the major studies in the record in its orderterminating the notice of inquiry.
Specifically, theCommission points to its statement that “[t]he vast majority offilings were unscientific.” 2019 Order, 34 FCC Rcd. at 11,694.

18
Elsewhere, however, the order acknowledges that “the record
include[d] some research information” and “filings that sought
to present scientific evidence.” Id. The order dismisses that
research and evidence as “fail[ing] to make a persuasive casefor revisiting our existing RF limits,” id., but again, such a
conclusory statement cannot substitute for the minimalreasoning required at this stage, Am. Radio, 524 F.3d at 241.
And while “[a]n agency is not obliged to respond to every
comment, only those that can be thought to challenge afundamental premise,” MCI WorldCom, Inc. v. FCC, 209 F.3d
760, 765 (D.C. Cir. 2000), the studies in the record to which
Petitioners point do challenge a fundamental premise of theCommission’s decision to terminate its notice of inquiry—
namely, the premise that exposure to RF radiation at levels
below the Commission’s current limits does not cause negative
health effects. But the Commission said nothing at all in its
order about any specific health effects unrelated to cancer.
The Commission also points to its statement that “therecord [does not] include actionable alternatives ormodifications to the current RF limits supported byscientifically rigorous data or analysis.” 2019 Order, 34 FCC
Rcd. at 11,692; see also id. at 11,694. Had the notice of inquiry
focused exclusively on whether the Commission should
modify its RF exposure limits, we might agree that the failureof any commenter to propose actionable modifications to the
RF limits would have justified the Commission’s decision toterminate the notice of inquiry. But the notice of inquiry did
not focus exclusively on whether the Commission should
modify its RF exposure limits. Instead, it also sought commenton how to better provide information to consumers and the
public about exposure to RF radiation and methods for
reducing exposure, and whether the Commission should
impose additional precautionary restrictions on devices andfacilities that are unlikely to expose people to RF radiation in19
excess of the Commission’s limits. The Commission needed
no actionable alternative to its current limits in order to provide
additional information to the public or to impose precautionary
restrictions in addition to its current limits. The failure of any
commenter to propose actionable modifications to theCommission’s RF exposure limits therefore does not justify theCommission’s decision to terminate the notice of inquiry.
ii.
The Commission’s failure to provide a reasoned
explanation for its determination that exposure to RF radiation
at levels below its current limits does not cause negative healtheffects unrelated to cancer renders the order arbitrary andcapricious in three additional respects. First, it undermines theCommission’s explanation for retaining its procedures fordetermining whether cell phones and other portable electronic
devices comply with its RF limits. These procedures consist of
testing the device against the head of a specialized mannequin,2013 Notice of Inquiry, 28 FCC Rcd. at 3,586 n.434, and no
more than 2.5 centimeters away from the body of themannequin, id. at 3,588 n.447. Petitioners claim that the testingis inaccurate because of the space between the device and themannequin’s body. On this point, the Commission’s ordercites the “large safety margin” incorporated in its existing RF
exposure limits as a justification for its refusal to modify theseprocedures to include testing against the body. 2019 Order, 34
FCC Rcd. at 11,696. Because the Commission’s existing RF
limits are overprotective, the order explains, the Commissionneed not worry about whether its testing procedures accurately
detect devices that are likely to expose people to RF emissions
in excess of the Commission’s limits. See id. (“[E]ven if
certified or otherwise authorized devices produce RF exposurelevels in excess of Commission limits under normal use, such
exposure would still be well below levels considered to be20
dangerous, and therefore phones legally sold in the UnitedStates pose no health risks.”). As the Commission itself
recognizes, this explanation depends on the premise that RF
radiation does not cause harmful effects at levels below its
current limits. See id. at 11,696 n.49 (“We note that any claim
as to the adequacy of the FCC required testing, certification,
and authorization regime is no different than a challenge to theadequacy of the federal RF exposure limits themselves. Bothtypes of claims would undermine the FCC’s substantive policy
determinations.”). The Commission’s failure to provide a
reasoned explanation for its determination that exposure to RF
radiation at levels below its current limits does not cause
negative health effects therefore renders inadequate theCommission’s explanation for its refusal to modify its testingprocedures.
Second, the Commission equally failed to provide a
reasoned explanation for brushing off record evidence
addressing non-cancer-related health effects arising from theimpact of RF radiation on children. Many commenters,
including the American Academy of Pediatrics, urged theCommission to adopt limits that account for the use of RFemitting devices by vulnerable children and pregnant women.
See, e.g., J.A. 4,533–34. In dismissing those concerns, theCommission again relied on a conclusory statement from the
FDA that “[t]he scientific evidence does not show a danger toany users of cell phones from RF exposure, including children
and teenagers.” 2019 Order, 34 FCC Rcd. at 11,696. But, as
we have already explained, such a conclusory and unexplained
statement is not the “reasoned” explanation required by the
APA. In addition, the Commission noted that the testing todetermine compliance with its limits “represents a conservativecase” for both adults and children. Id. at 11,696 n.50. Whether
the testing of compliance with existing limits was conservative
is not the point. The unanswered question remains whether low

21levels of RF radiation allowed by those existing limits cause
negative health effects. So once again, the Commission’s
failure to provide a reasoned or even relevant explanation of its
position that RF radiation below the current limits does notcause health problems unrelated to cancer renders its
explanation as to the effect of RF radiation on children arbitrary
and capricious.
Third, the Commission’s failure to provide a reasoned
explanation for its determination that exposure to RF radiation
at levels below its current limits does not cause negative healtheffects unrelated to cancer renders inadequate theCommission’s explanation for its failure to discuss theimplications of long-term exposure to RF radiation, exposure
to RF pulsation or modulation, or the implications oftechnological developments that have occurred since 1996,
including the ubiquity of wireless devices and Wi-Fi, and theemergence of “5G” technology. In its brief, the Commission
responds that it was not required to address these topics in its
order because it “rationally concluded that the weight ofscientific evidence does not support the existence of adverse
health effects from radiofrequency exposure below the FCC’slimits, regardless of the service or equipment at issue.”Resp’t’s Br. at 45–46. (The Commission points out that “5G”
cell towers, unlike traditional cell towers, are subject to its RF
exposure limits.) Again, this explanation depends on thepremise that RF radiation does not cause harmful health effects
at levels below the Commission’s current limits, and will not
suffice absent a reasoned explanation for the Commission’s
determination that that premise is correct.
iii.
In addition to the Commission’s inadequate response to
the non-cancer-related effects of RF radiation on human health,22
the Commission also completely failed even to acknowledge,
let alone respond to, comments concerning the impact of RF
radiation on the environment. That utter lack of a response
does not meet the Commission’s obligation to provide a
reasoned explanation for terminating the notice of inquiry. The
record contains substantive evidence of potential
environmental harms. Most relevantly, the record included aletter from the Department of the Interior voicing concern
about the impact of RF radiation from communication towers
on migratory birds, see J.A. 8,379, 8,383–86. In the
Department of the Interior’s expert view, the Commission’s RFradiation limits “continue to be based on thermal heating, acriterion now nearly 30 years out of date and inapplicable
today.” J.A. 8,383. “The [current environmental] problem,”according to the Department of the Interior, “appears to focus
on very low-level, non-thermal electromagnetic radiation.” Id.
Although the Commission has repeatedly claimed that it
considered “inputs from [its] sister federal agencies[,]” 2019
Order, 34 FCC Rcd. at 11,689, the Commission entirely failed
to address the environmental harm concerns raised by the
Department of the Interior. To be sure, the Commission could
conclude that the link between RF radiation and environmental
harms is too weak to warrant an amendment to its RF radiation
limits. All we hold now is that the Commission should havesaid something about its sister agency’s view rather than ignore
it altogether. That lack of any reasoned explanation as toenvironmental harms does not satisfy the requirements of the
APA.
iv.
The dissenting opinion portrays this case as about theCommission’s disregard of just five articles and one
Department of Interior letter. Not so. The record contained
substantial information and material from, for example, the23American Academy of Pediatrics, J.A. 4,533; the Council ofEurope, J.A. 4,242–44, 4,247–57; the Cities of Boston andPhiladelphia, J.A. 4,592–99; medical associations, see, e.g.,
J.A. 4,536–40 (California Medical Association); thousands ofphysicians and scientists from around the world, see, e.g., J.A.
4,197–4,206 (letter to United Nations); J.A. 4,208–17 (letter toEuropean Union); J.A. 5,173–86 (Frieburger Appeal by over
one thousand German physicians); and hundreds of people who
were themselves or who had loved ones suffering from thealleged effects of RF radiation, see, e.g., J.A. 8,774–9,940; seealso J.A. 4,218–39 (collecting statements from physicians andhealth organizations expressing concern about health effects of
RF radiation).
The dissenting opinion then offers its own explanation as
to why those select sources were not worth being addressed by
the agency. This in-the-weeds assessment of scientific studies
and assessments falls “outside our bailiwick[,]” Dissenting Op.
at 10. More to the point, the Commission said none of what
the dissenting opinion does. If it had and if those six sources
fairly represented the credible record evidence seeking achange in Commission policy, that discussion likely would
have sufficed. But just as post hoc rationales offered bycounsel cannot fill in the holes left by an agency in its decision,neither can a dissenting opinion. See Grace v. Barr, 965 F.3d
883, 903 (D.C. Cir. 2020) (“[W]hen ‘assessing thereasonableness of [an agency’s action], we look only to what
the agency said at the time of the [action]—not to its lawyers’
post-hoc rationalizations.’”) (second and third alterations inoriginal) (quoting Good Fortune Shipping SA v. Commissioner,
897 F.3d 256, 263 (D.C. Cir. 2018)).
Instead, the Commission chose to hitch its wagon to the
FDA’s unexplained disinterest in some similar information.
Importantly, the dissenting opinion does not dispute that the

24
FDA’s conclusory dismissal of that evidence ran afoul of ourprecedent in American Horse and American Radio. It just saysthat the deficiency in the FDA’s analysis cannot be imputed toa second agency, and so the dissenting opinion would holddispositive “the fact that the Commission and the FDA are, tostate the obvious, distinct agencies.” Dissenting Op. at 5.
They certainly are. But that does not amount to a legal
difference here. While imitation may be the highest form of
flattery, it does not meet even the low threshold of reasoned
analysis required by the APA under the deferential standard ofreview that governs here. One agency’s unexplained adoptionof an unreasoned analysis just compounds rather than vitiates
the analytical void. Said another way, two wrongs do not makea right. Compare City of Tacoma v. FERC, 460 F.3d 53, 76(D.C. Cir. 2006) (“[T]he action agency must not blindly adopt
the conclusions of the consultant agency, citing that agency’s
expertise. Rather, the ultimate responsibility for compliancewith the [Endangered Species Act] falls on the action
agency.”), and Ergon-West Virginia, Inc. v. EPA, 896 F.3d
600, 612 (4th Cir. 2018) (“Although the EPA is statutorily
required to consider the [Department of Energy]’s
recommendation, it may not turn a blind eye to errors andomissions apparent on the face of the report, which [petitioner]
pointed out and the EPA did not address in any meaningful
way. In doing so, the EPA ‘ignore[d] important aspects of the
problem.’”) (internal citations omitted), with Bellion Spirits,
LLC v. United States, No. 19-5252, slip op. at 13–14 (D.C. Cir.
Aug. 6, 2021) (approving consultation by the Alcohol andTobacco Tax and Trade Bureau (“TTB”) with the FDA where
the TTB “did not rubberstamp FDA’s analysis of the scientificevidence or delegate final decisionmaking authority to FDA,”
but instead “systematically evaluated and explained its reasonsfor agreeing with FDA’s analysis of each scientific study” and“then made its own determinations” about the claims at hand).

25
B.
Petitioners’ remaining challenges under the APA areunavailing.
Petitioners first argue that the Commission failed torespond to record evidence that exposure to RF radiation atlevels below the Commission’s current limits may cause
cancer. Specifically, Petitioners argue the Commission failed
to mention the IARC’s classification of RF radiation as
possibly carcinogenic to humans, and its 2013 monographregarding that classification, on which the Commission’s
notice of inquiry specifically sought comment. Petitioners also
argue that the Commission failed to adequately respond to two
2018 studies—the National Toxicology Program (“NTP”)
study and the Ramazzini Institute study—that found increases
in the incidences of certain types of cancer in rodents exposed
to RF radiation. Had these 2018 studies been available prior to
the IARC’s publication of its monograph, Petitioners assert, theIARC would have likely classified RF radiation as “probably
carcinogenic,” rather than “possibly carcinogenic.” This is so,according to Petitioners, because the IARC will classify anagent as “possibly carcinogenic” if there is “limited evidence”
that it causes cancer in humans and animals, and as “probably
carcinogenic” if there is “limited evidence” that it causes
cancer in humans and “sufficient evidence” that it causes
cancer in animals. In its 2013 monograph, the IARC found“limited evidence” that RF radiation causes cancer in humans
and animals, and therefore classified RF radiation as “possibly
carcinogenic.” Int’l Agency for Rsch. on Cancer, Non-Ionizing
Radiation, Part 2: Radiofrequency Electromagnetic Fields,
102 IARC MONOGRAPHS ON THE EVALUATION OF
CARCINOGENIC RISKS TO HUMANS 419 (2013) (emphases
omitted). Petitioners assert that the NTP and Ramazzini
Institute studies provide “sufficient evidence” that RF radiation26
causes cancer in animals. Therefore, according to Petitioners,
had those studies been available prior to the IARC’s
publication of its monograph, the IARC would have found“limited evidence” that RF radiation causes cancer in humans
and “sufficient evidence” that it causes cancer in animals, andwould have accordingly classified RF radiation as “probably
carcinogenic.”
Although the Commission’s failure to make any mentionof the IARC monograph does not epitomize reasoned decision
making, we find that the Commission’s order adequately
responds to the record evidence that exposure to RF radiation
at levels below the Commission’s current limits may cause
cancer. In contrast to its silence regarding non-cancerous
effects, the order provides a reasoned response to the NTP and
Ramazzini Institute studies. It explains that the results of the
NTP study “cannot be extrapolated to humans because (1) therats and mice received RF radiation across their whole bodies;(2) the exposure levels were higher than what people receive
under the current rules; (3) the duration of exposure was longer
than what people receive; and (4) the studies were based on 2G
and 3G phones and did not study WiFi or 5G.” 2019 Order, 34
FCC Rcd. at 11,693 n.33. And the order cites a response toboth studies published by the International Commission on
Non-Ionizing Radiation Protection that provides a detailed
explanation of various inconsistencies and limitations in thestudies and concludes that “consideration of their findings does
not provide evidence that radiofrequency EMF iscarcinogenic.” INT’L COMM’N ON NON-IONIZING RADIATION
PROT., ICNIRP NOTE ON RECENT ANIMAL CARCINOGENESISSTUDIES
6(2018),
https://www.icnirp.org/cms/
upload/publications/ICNIRPnote2018.pdf; see also 2019
Order, 34 FCC Rcd. at 11,693 n.34. Petitioners’ contention
that the IARC would have classified RF radiation as “probably
carcinogenic” had the NTP and Ramazzini Institute studies

27
been published earlier is speculative, particularly in light of theInternational Commission on Non-Ionizing Radiation
Protection’s evaluation of those studies. And the IARC
monograph’s classification of RF radiation as “possibly
carcinogenic” is not so contrary to the Commission’s
determination that exposure to RF radiation at levels below its
current limits does not cause cancer as to render that
determination arbitrary or capricious.
Petitioners also argue that the Commission’s orderimpermissibly fails to respond to various “additional legal
considerations.” Specifically, Petitioners argue that the order(i) ignores “express invocations of constitutional, statutory andcommon law based individual rights,” including property
rights and the rights of “bodily autonomy and informed
consent”; (ii) fails to explain whether FCC regulation preempts
rights and remedies under the Americans with Disabilities Act
and the Fair Housing Act; (iii) does not assess the costs andbenefits associated with maintaining the Commission’s current
limits; (iv) does not resolve the question of whether “thoseadvocating more protective limits have to prove the existing
limits are inadequate,” or whether the Commission carries theburden of proving that its existing limits are adequate; and (v)overlooks that the Supreme Court’s decision in Jacobson v.
Massachusetts, 197 U.S. 11 (1905), “flatly requires that theCommission allow for some remedy for those who suffer fromexposure.” Pet’rs’ Br. at 84–101.
These arguments are not properly before us. The
Communications Act provides that a petition forreconsideration is a “condition precedent to judicial review” of“questions of fact or law upon which the Commission . . . has
been afforded no opportunity to pass.” 47 U.S.C. § 405(a). We
will accordingly only consider a question raised before us if “areasonable Commission necessarily would have seen the28question . . . as part of the case presented to it.” NTCH, Inc. v.
FCC, 841 F.3d 497, 508 (D.C. Cir. 2016) (quoting Time
Warner Ent. Co. v. FCC, 144 F.3d 75, 81 (D.C. Cir. 1998)).
Petitioners did not submit a petition for reconsideration to theCommission, and they point to no comments raising their“additional legal considerations” in such a manner as tonecessarily indicate to the Commission that they were part ofthe case presented to it.
Although Petitioners assert that the “Cities of Boston andPhiladelphia specifically flagged [the issue of whether FCC
regulation preempts rights and remedies under the Americans
with Disabilities Act and the Fair Housing Act] and soughtclarification,” Pet’rs’ Br. at 86, they are incorrect. The Cities
of Boston and Philadelphia merely observed that the Second
Circuit’s decision in Cellular Phone Taskforce did not address
whether “‘electrosensitivity’ [is] a cognizable disability underthe Americans with Disabilities Act,” J.A. 4,598. And the
Cities noted that “the FCC and its sister regulatory agencies
share responsibility for adherence to the ADA,” J.A. 4,598–99,
and urged the Commission to “lead in advice to electrosensitive
persons about prudent avoidance,” J.A. 4,599. This did not put
the Commission on notice that the question whether FCC
regulation preempts rights and remedies under the Americans
with Disabilities Act and the Fair Housing Act was part of thecase presented to it. Nor did a comment asserting that “[t]hetelecommunications Act should not be interpreted to injure an
identifiable segment of the population, exile them from theirhomes and their city, leave them no place where they cansurvive, and allow them no remedy under City, State or Federal
laws or constitutions.” J.A. 10,190. And Petitioners point tono comments that did a better job of flagging their other“additional legal considerations” for the Commission. The
Commission therefore did not have an opportunity to pass on29these arguments, so we may not review them. 47 U.S.C.
§ 405(a).
C.
Petitioners also argue that NEPA required the Commission
to issue an EA or EIS regarding its decision to terminate its
notice of inquiry.
Petitioners are wrong. The Commission was not required
to issue an EA or EIS because there was no ongoing federal
action regarding its RF limits. The Commission alreadypublished an assessment of its existing RF limits that“‘functionally’ satisfied NEPA’s requirements ‘in form andsubstance.’” EMR Network, 391 F.3d at 272 (quoting Cellular
Phone Taskforce, 205 F.3d at 94–95). NEPA obligations attach
only to “proposals” for major federal action. See 42 U.S.C. §4332(c); see also 40 C.F.R. § 1502.5. Once an agency has
satisfied NEPA’s requirements, it is only required to issue a
supplemental assessment when “there remains major federal
action to occur.” W. Org. of Res. Councils v. Zinke, 892 F.3d
1234, 1242 (D.C. Cir. 2018) (internal quotation marks omitted)(quoting Marsh v. Ore. Nat’l Res. Council, 490 U.S. 360, 374(1989)). An agency’s promulgation of regulations constitutes
a final agency action that is not ongoing. Id. at 1243. Once anagency promulgates a regulation and complies with NEPA’s
requirements regarding that regulation, it is not required to
conduct any supplemental environmental assessment, even if
its original assessment is outdated. Id. at 1242. Such is thecase here. As we explained in EMR Network in response to theargument that new data required the Commission to issue a
supplemental environmental assessment of its RF guidelines
under NEPA, “the regulations having been adopted, there is at
the moment no ongoing federal action, and no duty to30
supplement the agency’s prior environmental inquiries.” 391
F.3d at 272 (internal quotation marks and citation omitted).
That the Commission voluntarily initiated an inquiry to“determine whether there is a need for reassessment of theCommission radiofrequency (RF) exposure limits andpolicies” does not change the analysis. 2013 Notice of Inquiry,
28 FCC Rcd. at 3,501. As the Supreme Court explained long
ago, “the mere contemplation of certain action is not sufficient
to require an impact statement” under NEPA, Kleppe v. Sierra
Club, 427 U.S. 390, 404 (1976) (internal quotation marks
omitted), because, as in this case, “the contemplation of a
project and the accompanying study thereof do not necessarily
result in a proposal for major federal action,” id. at 406. See
also Pub. Citizen v. Off. of U.S. Trade Representatives, 970
F.2d 916, 920 (D.C. Cir. 1992) (“In accord with Kleppe, courts
routinely dismiss NEPA claims in cases where agencies are
merely contemplating a particular course of action but have notactually taken any final action at the time of suit.”) (collecting
cases). Were the Commission to propose revising its RF
exposure guidelines, it might be required to prepare NEPA
documentation. But since the Commission for now has notproposed to alter its guidelines, it need not yet conduct any new
environmental review.
III.
For the reasons given above, we grant the petitions in partand remand to the Commission to provide a reasoned
explanation for its determination that its guidelines adequately
protect against harmful effects of exposure to radiofrequency
radiation unrelated to cancer. It must, in particular, (i) provide
a reasoned explanation for its decision to retain its testingprocedures for determining whether cell phones and otherportable electronic devices comply with its guidelines, (ii)31
address the impacts of RF radiation on children, the health
implications of long-term exposure to RF radiation, theubiquity of wireless devices, and other technologicaldevelopments that have occurred since the Commission last
updated its guidelines, and (iii) address the impacts of RF
radiation on the evironment. To be clear, we take no positionin the scientific debate regarding the health and environmental
effects of RF radiation—we merely conclude that theCommission’s cursory analysis of material record evidence
was insufficient as a matter of law. As the dissenting opinion
indicates, there may be good reasons why the various studies
in the record, only some of which we have cited here, do not
warrant changes to the Commission’s guidelines. But wecannot supply reasoning in the agency’s stead, see SEC v.
Chenery Corp., 318 U.S. 80, 87–88 (1943), and here theCommission has failed to provide any reasoning to which we
may defer.
So ordered.

KAREN LECRAFT HENDERSON, Circuit Judge, dissenting
in part: “[A] court is not to substitute its judgment for that of
the agency.” Motor Vehicle Mfrs. Ass’n v. State Farm Mut.
Auto. Ins. Co., 463 U.S. 29, 43 (1983). We thus must “upholda decision of less than ideal clarity if the agency’s path may
reasonably be discerned.” Id. (quoting Bowman Transp., Inc. v.
Arkansas-Best Freight Sys., Inc., 419 U.S. 281, 286 (1974)). I
believe my colleagues’ limited remand contravenes these firstprinciples of administrative law. Because I would deny thepetitions in full, I respectfully dissent from Part II.A.i.–iv. andPart III of the majority opinion.
I.
It is important to emphasize how deferential our standardof review is here—where, first, an agency’s decision toterminate a notice of inquiry without initiating a rulemaking
occurred after the agency opened the inquiry on its own and,second, the inquiry involves a highly technical subject matterat the frontier of science. As the majority recognizes, “[t]hearbitrary and capricious standard of the Administrative
Procedure Act ‘encompasses a range of levels of deference tothe agency.’” Maj. Op. 8 (quoting Am. Horse Prot. Ass’n v.
Lyng, 812 F.2d 1, 4 (D.C. Cir. 1987)). The majority further
acknowledges that the Federal Communications Commission’s(Commission or FCC) “order is entitled to a high degree ofdeference.” Id. at 9. And our precedent also makes plain that“[i]t is only in the rarest and most compelling of circumstancesthat this court has acted to overturn an agency judgment not toinstitute rulemaking.” WWHT, Inc. v. FCC, 656 F.2d 807, 818(D.C. Cir. 1981); see also Cellnet Commc’n, Inc. v. FCC, 965
F.2d 1106, 1111 (D.C. Cir. 1992) (“an agency’s refusal toinitiate a rulemaking is evaluated with a deference so broad as
to make the process akin to non-reviewability”). For thereasons that follow, I believe the Commission’s order does not
fit those rarest and most compelling circumstances.

2
A.
We have held that research articles containing tentative
conclusions do not provide a basis for disturbing an agency’s
decision not to initiate rulemaking. See EMR Network v. FCC,
391 F.3d 269, 274 (D.C. Cir. 2004). Nevertheless, the majority
rejects reaching the same conclusion here regarding thepetitioners’ assertion that radiofrequency (RF) radiation
exposure below the Commission’s limits can cause negative
health effects unrelated to cancer. To do so, it relies on fiveresearch articles in an over 10,500-page record. See Maj. Op.
at 10–11.1
A close inspection of the five research articles confirmsthat they also “are nothing if not tentative.” EMR Network, 391
F.3d at 274. The Foerster article concludes “[o]ur findings do
not provide conclusive evidence of causal effects and should beinterpreted with caution until confirmed in other populations.”
Joint Appendix (J.A.) 6,006 (Milena Foerster et al., A
Prospective Cohort Study of Adolescents’ Memory
Performance and Individual Brain Dose of Microwave
Radiation from Wireless Communication, 126 ENV’T HEALTHPERSPS. 077007 (July 2018)) (emphases added).2 The Lai

1“The record in an informal rulemaking proceeding is ‘a lessthan fertile ground for judicial review’ and has been described as a‘sump in which the parties have deposited a sundry mass ofmaterials.’” Pro. Drivers Council v. Bureau of Motor Carrier Safety,
706 F.2d 1216, 1220–21 (D.C. Cir. 1983) (quoting Nat’l Res. Def.
Council, Inc. v. SEC, 606 F.2d 1031, 1052 (D.C. Cir. 1979)).
2
See also J.A. 5,995 (“[T]he health effects of [exposure toradiofrequency electromagnetic fields (RF-EMFs)] are still
unknown. . . . [T]o date studies addressing this topic have produced
inconsistent results.”); J.A. 6,005 (“Although we found decreases infigural memory, some experimental and epidemiological studies on

3article provides a similarly murky picture of the current
science. See J.A. 5,320–68 (Henry Lai, A Summary of Recent
Literature (2007–2017) on Neurological Effects ofRadiofrequency Radiation, in MOBILE COMMC’NS & PUB.
HEALTH 187–222 (M. Markov ed., 2018)). In summarizing theresults of human studies on the behavioral effects of RF
radiation, the Lai article lists 31 studies that showed nosignificant behavioral effects compared to 20 studies thatshowed behavioral effects. See J.A. 5,327–32. Moreover, of the
20 studies that showed a behavioral effect, at least four foundbehavioral improvements, not negative health effects.
Even the Yakymenko article, which asserts that 93 of 100
peer-reviewed studies found low-intensity RF radiationinduces oxidative effects in biological systems, fails to address
the critical issue—whether RF radiation below theCommission’s current limits can cause negative health effects.
See J.A. 5,243–58 (Igor Yakymenko et al., Oxidative
Mechanisms of Biological Activity of Low-Intensity
Radiofrequency Radiation, ELECTROMAGNETIC BIOLOGY &MED., EARLY ONLINE, 1–16 (2015)). Specifically, theYakymenko article discusses the International Commission on
Non-Ionizing Radiation Protection’s (ICNIRP) recommended
RF exposure limit—a specific absorption rate of 2 W/kg. See
J.A. 5,243–44. But the ICNIRP’s recommended RF exposure
limit is significantly higher than the Commission’s current
limit—0.08 W/kg averaged over the whole body and a peakspatial-average of 1.6 W/kg over any 1 gram of tissue. See 47
C.F.R. § 1.1310(c). Accordingly, it is uncertain how many, if

RF-EMF found improvements in working memory performance.”)(emphasis added).

4any, of the referenced peer-reviewed studies were conducted at
RF radiation levels below the Commission’s current limits.3
Given this record, I believe we should have arrived at thesame conclusion we did in EMR Network—“nothing in th[e]sestudies so strongly evidenc[es] risk as to call into question theCommission’s decision to maintain a stance of what appears to
be watchful waiting.” EMR Network, 391 F.3d at 274. “Anagency is not obliged to respond to every comment, only thosethat can be thought to challenge a fundamental premise.” MCIWorldCom, Inc. v. FCC, 209 F.3d 760, 765 (D.C. Cir. 2000).
A review of the five articles on which the majority opinion
relies makes plain that the articles do not challenge afundamental premise of the Commission’s order. Instead, it“cherry-pick[s] the factual record to reach [its] conclusion.”
Ortiz-Diaz v. U.S. Dep’t of Hous. & Urb. Dev., 867 F.3d 70, 79(D.C. Cir. 2017) (Henderson, J., concurring in the judgment).
My colleagues assert that “[t]he dissenting opinion
portrays this case as about the Commission’s disregard of justfive articles.” Maj. Op. 22. But their attempt to “turn the tables”
plainly fails. It is they who chose the five articles, see Maj. Op.
10–11, to rely on as the basis for their remand, see id. at 15(“the Commission’s order remains bereft of any explanation as
to why, in light of the studies in the record, its guidelines
remain adequate”) (emphasis altered); id. at 18 (“the studies in
the record to which Petitioners point do challenge afundamental premise of the Commission’s decision toterminate its notice of inquiry”) (first emphasis added). I
discuss the five articles only to demonstrate that the studies “arenothing if not tentative.” EMR Network, 391 F.3d at 274.
Because the studies on which the majority relies plainly are
3

The BioInitiative Report the majority opinion cites is hardly
worth discussing because the self-published report has been widelydiscredited as a biased review of the science.

5
tentative, they do not challenge a fundamental premise of theCommission’s decision and therefore cannot provide the basis
for the majority’s limited remand under our precedent.4
B.
I reach the same conclusion regarding the majority’s
remand of the petitioners’ environmental harm argument. See
Maj. Op. 21–22. The majority relies on a 2014 letter from the
U.S. Department of the Interior (Interior) to the U.S.
Department of Commerce about, inter alia, the impact ofcommunications towers on migratory birds. But the Interior
letter itself concedes that “[t]o date, no independent, third-party
field studies have been conducted in North America on impactsof tower electromagnetic radiation on migratory birds.” J.A.
8,383.
Moreover, the petitioners did not raise the Interior letter inthe environmental harm section of their briefs. “We apply
forfeiture to unarticulated [legal and] evidentiary theories not
only because judges are not like pigs, hunting for truffles
buried in briefs or the record, but also because such a ruleensures fairness to both parties.” Jones v. Kirchner, 835 F.3d
74, 83 (D.C. Cir. 2016) (alteration in original) (citation
omitted). And finally, the environmental harm studies on which

4

The majority’s hand wave to other record information, seeMaj. Op. 22–23, does not carry the day. Rather than provide“substantial information,” id. at 22, the cited material consists
primarily of letters expressing generalized concerns about RF limits
worldwide.

6
the petitioners did rely “are nothing if not tentative.” EMR
Network, 391 F.3d at 274.5
C.
More importantly, the majority’s limited remand runs
afoul of our precedent on this precise subject matter. In EMR
Network, the petitioner asked “the Commission to initiate an
inquiry on the need to revise [its] regulations to address the
non-thermal effects” of RF radiation. 391 F.3d at 271. In
denying the petition, we concluded “the [Commission]’s
decision not to leap in, at a time when the [Environmental
Protection Agency (EPA)] (and other agencies) saw nocompelling case for action, appears to represent the sort ofpriority-setting in the use of agency resources that is least
subject to second-guessing by courts.” Id. at 273.
This time around, the majority faults the Commission for
the U.S. Food and Drug Administration’s (FDA) allegedly“conclusory statements” in response to the Commission’s 2013
notice of inquiry. See Maj. Op. 14. The crux of the majority’s
position is that “[t]he statements from the FDA on which theCommission’s order relies are practically identical to theSecretary’s statement in American Horse and the5See, e.g., J.A. 5,231 (Albert Manville, II, A Briefing
Memorandum: What We Know, Can Infer, and Don’t Yet Know
about Impacts from Thermal and Non-Thermal Non-Ionizing
Radiation to Birds and Other Wildlife 2 (2016)) (“the direct
relationship between electromagnetic radiation and wildlife healthcontinues to be complicated and in cases involving non-thermal
effects, still unclear”); J.A. 6,174 (Ministry of Env’t & Forest, Gov’tof India, Report on Possible Impacts of Communication Towers on
Wildlife Including Birds and Bees 4 (2011)) (“exact correlation
between radiation of communication towers and wildlife, are not yetvery well established”).

7
Commission’s statement in American Radio.” Id.6 But theanalogy to American Horse and American Radio does not holdwater. The majority’s Achilles’ heel is the fact that theCommission and the FDA are, to state the obvious, distinct
agencies.
In American Horse, the appellant relied on the results of astudy commissioned by the U.S. Department of Agriculture(Agriculture) to support its request for revised Agriculture
regulations. Am. Horse, 812 F.2d at 2–3. The study found thatdevices Agriculture had declined to prohibit caused effects
falling within the statutory definition of the condition known
as “sore”;7 and the Congress had charged Agriculture toeliminate the practice of soring show horses. Am. Horse, 812
F.2d at 2–3. Against this backdrop, we found the Agriculture
Secretary’s “two conclusory sentences [dismissing the need torevise agency regulations] . . . insufficient to assure areviewing court that the agency’s refusal to act was the productof reasoned decisionmaking.” Id. at 6. But an agency head’sterse dismissal of his own agency’s study is not the case here.
First, as noted supra, there is no conclusive study in the record,much less one commissioned by the agency whose regulations
are being considered for revision. Instead, the record contains
dozens of highly technical studies from various sources—thecredibility and findings of which we are ill-equipped toevaluate. And crucially, unlike in American Horse, theCommission requested the opinion of the FDA—the agency
charged with “establish[ing] and carry[ing] out an electronic
6

See Am. Radio Relay League, Inc. v. FCC, 524 F.3d 227 (D.C.
Cir. 2008).
7
See 15 U.S.C. § 1821(3) (“The term ‘sore’ when used todescribe a horse means that [as a result of any substance or device
used on a horse’s limb] such horse suffers, or can reasonably be
expected to suffer, physical pain or distress, inflammation, or
lameness when walking, trotting, or otherwise moving . . . .”).

8
product radiation control program,” 21 U.S.C. § 360ii(a)—studied that opinion and explained why it relied thereon in
making its decision.
Similarly, in American Radio, the studies summarily
dismissed by the FCC were studies the FCC sought to evaluate
itself; we remanded for the FCC to explain why it failed to doso. See Am. Radio, 524 F.3d at 241. Moreover, American Radio
addressed the reasoning underlying the FCC’s promulgation ofa rule, an action subjected to far less deference than an agency’s
decision not to initiate a rulemaking.8
I believe the Commission reasonably relied on the
conclusions of the FDA, the agency statutorily charged withprotecting the public from RF radiation. See 21 U.S.C.
§ 360ii(a) (FDA “shall establish and carry out an electronic
product radiation control program designed to protect the
public health and safety from electronic product radiation”).9
Our precedent is well-settled that “[a]gencies can be expected
to ‘respect [the] views of such other agencies as to those
8

See, e.g., ITT World Commc’ns, Inc. v. FCC, 699 F.2d 1219,
1245–46 (D.C. Cir. 1983), rev’d on other grounds, 466 U.S. 463(1984) (“Where an agency promulgates rules, our standard of review
is diffident and deferential, but nevertheless requires a searching andcareful examination of the administrative record to ensure that theagency has fairly considered the issues and arrived at a rational
result. Where, as here, an agency chooses not to engage inrulemaking, our level of scrutiny is even more deferential . . .”(emphasis in original) (footnotes and internal quotations omitted)).
9
See also In re Guidelines for Evaluating the Env’t Effects ofRadiofrequency Radiation, 11 FCC Rcd. 15,123, 15,130 ¶ 18 (1996)(“The FDA has general jurisdiction for protecting the public frompotentially harmful radiation from consumer and industrial devices
and in that capacity is expert in RF exposures that would result fromconsumer or industrial use of hand-held devices such as cellular
telephones.”).

9
problems’ for which those ‘other agencies are more directly
responsible and more competent.’” City of Bos. Delegation v.
FERC, 897 F.3d 241, 255 (D.C. Cir. 2018) (second alterationin original) (quoting City of Pittsburgh v. Fed. Power Comm’n,
237 F.2d 741, 754 (D.C. Cir. 1956)). That is precisely what theCommission did here.
The Commission’s 2013 Notice of Inquiry explained that
the Commission intended to rely on, inter alia, the FDA todetermine whether to reassess its own RF exposure limits. See
In re Reassessment of Fed. Commc’ns Comm’nRadiofrequency Exposure Limits & Policies, 28 FCC Rcd.
3,498, 3,501 ¶ 6 (2013) (2013 Notice of Inquiry) (“Since theCommission is not a health and safety agency, we defer to otherorganizations and agencies with respect to interpreting thebiological research necessary to determine what [RF radiation]levels are safe.”). And the Commission has consistently
deferred to expert health and safety agencies in this context.
See id. at 3,572 ¶ 211 (RF exposure limits adopted in 1996
“followed recommendations received from the [EPA], the[FDA], and other federal health and safety agencies”).10
The Commission was true to its word. On March 22, 2019,it asked the FDA if changes to the RF exposure limits were10

See also In re Guidelines for Evaluating the Env’t Effects ofRadiofrequency Radiation, 12 FCC Rcd. 13,494, 13,505 ¶ 31 (1997)(“It would be impracticable for us to independently evaluate thesignificance of studies purporting to show biological effects,
determine if such effects constitute a safety hazard, and then adopt
stricter standards that [sic] those advocated by federal health andsafety agencies. This is especially true for such controversial issues
as non-thermal effects and whether certain individuals might be‘hypersensitive’ or ‘electrosensitive.’”).

10
warranted by the current scientific research.11 On April 24,
2019, the FDA responded:
FDA is responsible for the collection andanalysis of scientific information that may
relate to the safety of cellphones and otherelectronic products. . . . As we have statedpublicly, . . . the available scientific evidence todate does not support adverse health effects inhumans due to exposures at or under the current
limits, and . . . the FDA is committed toprotecting public health and continues its
review of the many sources of scientific
literature on this topic.
J.A. 8,187 (Letter from Jeffrey Shuren, M.D., J.D., Dir., Ctr.
for Devices and Radiological Health, U.S. Food & Drug
Admin., Dep’t of Health & Hum. Servs., to Julius Knapp,
Chief, Off. of Eng’g & Tech., U.S. Fed. Commc’ns Comm’n(April 24, 2019)).12 In my view, the Commission, relying on
11

See J.A. 8,184 (Letter from Julius Knapp, Chief, Off. of Eng’g& Tech., U.S. Fed. Commc’ns Comm’n, to Jeffrey Shuren, M.D.,
J.D., Dir., Ctr. for Devices and Radiological Health, U.S. Food &Drug Admin. (March 22, 2019)) (“Given that existing studies arecontinually being evaluated as new research is published, and thatthe work of key organizations such as [the Institute of Electrical andElectronics Engineers] and ICNIRP is continuing, we ask FDA’s
guidance as to whether any changes to the standards are appropriate
at this time.”).
12
See also Statement from Jeffrey Shuren, M.D., J.D., directorof the FDA’s Center for Devices and Radiological Health on the
recent National Toxicology Program draft report on radiofrequency
energy exposure, FOOD & DRUG ADMIN. (Feb. 2, 2018),
https://www.fda.gov/news-events/press-announcements/statementjeffrey-shuren-md-jd-director-fdas-center-devices-and-radiologicalhealth-recent-national (Since 1999, “there have been hundreds of

11
the FDA, reasonably concluded no changes to the current RF
exposure limits were warranted at the time. See In re
Reassessment of Fed. Commc’ns Comm’n Radiofrequency
Exposure Limits & Policies, 34 FCC Rcd. 11,687, 11,691 ¶ 10(2019) (2019 Order).
Simply put, the Commission’s reliance on the FDA isreasonable “[i]n the face of conflicting evidence at the frontiersof science.” See Cellular Phone Taskforce v. FCC, 205 F.3d
82, 90 (2d Cir. 2000). The majority takes issue with what it
categorizes as “conclusory statements.” Maj. Op. 14. But theSupreme Court’s “State Farm [decision] does not require aword count; a short explanation can be a reasoned
explanation.” Am. Radio, 524 F.3d at 247 (Kavanaugh, J.,dissenting in part). Brevity is even more understandable if theagency whose rationale is challenged relies on the agency theCongress has charged with regulating the matter.
Granted, “[w]hen an agency in the Commission’s position
is confronted with evidence that its current regulations are
inadequate or the factual premises underlying its priorjudgment have eroded, it must offer more to justify its decision
to retain its regulations than mere conclusory statements.” Maj.
studies from which to draw a wealth of information about thesetechnologies which have come to play an important role in our
everyday lives. Taken together, all of this research provides a more
complete picture regarding radiofrequency energy exposure that has
informed the FDA’s assessment of this important public health issue,and given us the confidence that the current safety limits for cell
phone radiation remain acceptable for protecting the publichealth. . . . I want to underscore that based on our ongoing evaluationof this issue and taking into account all available scientific evidence
we have received, we have not found sufficient evidence that there
are adverse health effects in humans caused by exposures at or under
the current radiofrequency energy exposure limits.”).

12
Op. 9. But the majority opinion rests on an inaccurate
premise—the Commission was not confronted with evidence
that its regulations are inadequate nor have the factual premises
underlying its RF exposure limits eroded. Sifting through therecord’s technical complexity is outside our bailiwick. If therecord here establishes one point, however, it is that there is no
scientific consensus regarding the “non-thermal” effects, ifany, of RF radiation on humans. More importantly, the FDA,
not the Commission, made the allegedly “conclusory
statements” with which the majority takes issue and I believe
the Commission adequately explained why it relied on the
FDA’s expertise.13

13

The majority asserts that “[o]ne agency’s unexplained
adoption of an unreasoned analysis just compounds rather thanvitiates the analytical void.” Maj. Op. 24. As set out supra, however,
the Commission adequately explained its reliance—for the past 25
years—on the FDA’s RF exposure expertise. Plus, after a review of“hundreds of studies,” the FDA’s conclusion is far from unreasoned.
See supra note 12. And the two cases to which the majority points
are inapposite. See Maj. Op. 24 (citing City of Tacoma v. FERC, 460
F.3d 53, 76 (D.C. Cir. 2006), and Ergon-West Virginia, Inc. v. EPA,
896 F.3d 600, 612 (4th Cir. 2018)). Importantly, unlike thesepetitions, neither case involves a decision not to initiate arulemaking. As noted, inaction is reviewed under an especiallydeferential standard. It would be inappropriate to apply precedentusing a less deferential standard to modify the standard applicablehere. And finally, the Commission did not “blindly adopt theconclusions” of the FDA. See City of Tacoma, 460 F.3d at 76. Nor
did it “turn a blind eye to errors and omissions apparent on the faceof” the FDA’s conclusions. See Ergon-West Virginia, 896 F.3d at
612.
The majority’s citation to Bellion Spirits, LLC v. United States,
No. 19-5252 (D.C. Cir. Aug. 6, 2021), is even further afield. First,
Bellion Spirits addressed a “statutory authority” question—it did not
apply arbitrary and capricious review, much less the especially13
As in EMR Network, the record does not “call into question
the Commission’s decision to maintain a stance of what
appears to be watchful waiting.” 391 F.3d at 274. To holdotherwise begs the question: what was the Commission
supposed to do? It has no authority over the level of detail the
FDA provides in response to the Commission’s inquiry. It
admits that it does not have the expertise “to interpret[] thebiological research necessary to determine what [RF radiation]levels are safe.” 2013 Notice of Inquiry, 28 FCC Rcd. at 3,501¶ 6. The Commission opened the 2013 Notice of Inquiry “as amatterofgoodgovernment”
despiteits“continue[d] . . . confidence in the current [RF] exposure
limits.” Id. at 3,570 ¶ 205. If it had reached a conclusion
contrary to the FDA’s, it most likely would have been attacked
as ultra vires. For us to require the Commission to, in effect,“nudge” the FDA stretches both our jurisdiction as well as its
authority beyond recognized limits.
Accordingly, I respectfully dissent from the limited
remand set forth in Part II.A.i.–iv. and Part III of the majority
opinion.14
deferential standard applicable to a decision not to initiate arulemaking. See Bellion Spirits, slip op. at 13. Second, to the extent
Bellion Spirits is remotely relevant, I believe it supports my position.
There, the Alcohol and Tobacco Tax and Trade Bureau “consulted
with [the] FDA on a matter implicating [the] FDA’s expertise andthen considered that expertise in reaching its own final decision.” Id.
at 14. Again, in my view, the Commission did the same thing.
14
Although I join Part II.B. of the majority opinion, I do notagree with the majority’s aside, contrasting the Commission’s
purported silence regarding non-cancerous effects and its otherwise
reasoned response. See Maj. Op. 26. As explained supra, I believe
the Commission reasonably relied on the FDA’s conclusion that RF
radiation exposure below the Commission’s limits does not cause
negative health effects—cancerous or non-cancerous.