Court Opinion

ID: 9906949
Source: CourtListenerOpinion
Date Created: 2023-12-05 17:01:34.435601+00
Date Added: 2024-06-11T09:54:49.305871
License: Public Domain

Appellate Case: 22-4082     Document: 010110963219   Date Filed: 12/05/2023   Page: 1
                                                                          FILED
                                                              United States Court of Appeals
                                     PUBLISH                          Tenth Circuit

                      UNITED STATES COURT OF APPEALS               December 5, 2023

                                                                 Christopher M. Wolpert
                             FOR THE TENTH CIRCUIT                   Clerk of Court

  IAN C.; A.C.,

         Plaintiffs - Appellants,

  v.                                                     No. 22-4082

  UNITEDHEALTHCARE
  INSURANCE COMPANY,

         Defendant - Appellee.

  ------------------------------

  CHAMBER OF COMMERCE OF THE
  UNITED STATES OF AMERICA,

         Amicus Curiae.

                   Appeal from the United States District Court
                             for the District of Utah
                         (D.C. No. 2:19-CV-00474-HCN)

 Brian Smith King of Brian S. King P.C., Salt Lake City, Utah, for Plaintiffs -
 Appellants.

 Amanda Shafer Berman of Crowell & Moring LLP, Washington, D.C. (Amy M.
 Pauli, Neil Nandi, and Samuel H. Ruddy of Crowell & Moring LLP,
 Washington, D.C., and Jennifer S. Romano of Crowell & Moring LLP, Los
 Angeles, California, with her on the brief) for Defendant - Appellee.

 Tara Morrissey, U.S. Chamber Litigation Center, Washington, D.C.; Meaghan
 VerGow, O’Melveny & Myers LLP, Washington, D.C., filed an amicus curiae
 brief on behalf of Defendant - Appellee, for the United States of America.
Appellate Case: 22-4082   Document: 010110963219      Date Filed: 12/05/2023   Page: 2

 Before BACHARACH, PHILLIPS, and EID, Circuit Judges.

 PHILLIPS, Circuit Judge.

       This appeal arises from an action under the Employee Retirement Income

 Security Act of 1974 (ERISA), 29 U.S.C. §§ 1001–1461, to challenge the denial

 of healthcare benefits through an employer-sponsored plan. Ian C., the plan

 participant, claimed coverage for his son, A.C., the beneficiary, to receive care

 at an inpatient residential treatment center, Catalyst Residential Treatment, for

 mental-health and substance-abuse issues. The plan authorized

 UnitedHealthcare Insurance Company (United), the claims fiduciary, to

 determine A.C.’s eligibility for benefits under the plan. 1 After initially covering

 A.C.’s treatment at Catalyst, United later denied coverage.

       Ian C. internally appealed the adverse benefit determination, which

 United upheld on appeal. Ian C. then pursued his case against United in federal

 district court, where he alleged that United’s denial violated his right to receive

 a “full and fair review” of his claim under 29 U.S.C. §§ 1133(2), 1104(a)(1). 2

       1
         United administered benefits for mental-health and substance-abuse
 services through its designee, United Behavioral Health. We refer to these
 entities collectively as “United.”
       2
         Ian C. and A.C. are both named plaintiffs on the complaint filed in the
 U.S. District Court for the District of Utah and are both named as appellants on
 the notice of appeal to this court. But for concision, we refer to the appellants
 collectively under the guise of “Ian C.,” as the covered plan participant and
 parent of the claimed beneficiary.
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 Ian C. argued that United arbitrarily and capriciously denied benefits to A.C.

 by failing to address A.C.’s substance abuse as an independent ground for

 coverage, by determining that A.C.’s continued treatment at Catalyst was not

 medically necessary, by ignoring the opinions of A.C.’s medical providers, and

 by misapplying the appropriate level-of-care guidelines. United denied these

 claims, and the parties filed competing motions for summary judgment. Ruling

 on dual motions for summary judgment, the district court decided in favor of

 United. Ian C. now appeals the district court’s ruling that United’s decision to

 deny benefits was not arbitrary and capricious and complied with ERISA.

       Exercising jurisdiction under 28 U.S.C. § 1291, we agree with Ian C. that

 United’s decision to deny benefits was arbitrary and capricious. We hold that

 United’s denial violated 29 U.S.C. § 1133(2) and the ERISA regulations that

 guarantee a “full and fair review” of claims raised under § 1132(a)(1)(B), and

 so we reverse.

                                 BACKGROUND

 I.    Factual Background

       A.     Ian C.’s Plan

       Ian C.’s employer-sponsored benefits plan provides that United may

 decide “whether [the] Benefit plan will pay for any portion of the cost of a

 health care service,” “[i]nterpret Benefits and the other terms, limitations and

 exclusions set out in [the plan],” and “[m]ake factual determinations relating to

 Benefits.” App. vol. 8, at 13. The plan covers services for mental health and

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 substance abuse, specifically treatment at a residential treatment facility. But

 even these ostensibly covered services must be “[m]edically [n]ecessary” for

 United to extend benefits. Id. at 40, 45. And only United, or its designee, may

 determine medical necessity at its discretion.

       To determine which services are medically necessary, United follows

 level-of-care guidelines for each area of service that it covers. For example, the

 guidelines for Common Criteria and Clinical Best Practices (Common Criteria

 Guidelines) establish general standards for admission, continued coverage, and

 discharge at a residential treatment facility. United also has more specific

 guidelines tailored to services for mental health and substance abuse—

 guidelines for the Mental Health Residential Treatment Center (Mental Health

 Guidelines) and guidelines for Substance-Related Disorders (Substance Abuse

 Guidelines).

       The Common Criteria Guidelines advise United to cover a beneficiary’s

 admission to a residential treatment facility if “the member is eligible for

 benefits,” and the “member’s current condition cannot be safely, efficiently,

 and effectively assessed and/or treated in a less intensive level of care.” App.

 vol. 9, at 33–34. For United to cover “continued service,” the Guidelines

 recommend that the “admission criteria continue to be met and active treatment

 is being provided.” Id. at 34. And the Guidelines direct United to stop service

 and discharge the beneficiary when the “factors which led to admission have

 been addressed” and “the member can be safely transitioned to a less intensive

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 level of care.” Id. at 35. The Mental Health Guidelines and Substance Abuse

 Guidelines incorporate the Common Criteria Guidelines by reference.

       Ian C.’s plan also provides a process for appealing adverse benefit

 determinations. Upon receiving a claim denial, the plan allows Ian C. to appeal

 the decision to United within 180 days. United then assigns the decision to be

 reviewed by a “qualified individual . . . who was not involved in the prior

 determination.” App. vol. 8, at 61. If the appeal is denied, then the decision is

 final and the internal appeals process is exhausted.

       B.     A.C.’s Treatment History

       A.C. was seventeen when Catalyst admitted him for mental-health and

 substance-abuse treatment, but these problems had dogged him since childhood.

 A.C. was diagnosed with Attention Deficit Hyperactivity Disorder at age seven.

 This diagnosis put him on medication for the first time, which caused him to

 feel withdrawn and not like himself. A.C. struggled with schoolwork through

 elementary and middle school, which strained his relationship with his parents.

 At thirteen, clinical psychologist Dr. Walter Peacock diagnosed A.C. with

 Anxiety Disorder. Dr. Peacock began meeting regularly with A.C. and his

 family to manage A.C.’s anxiety and “unhealthy relationship” with his parents.

 App. vol. 3, at 52. This outpatient therapy proved unsuccessful. By high school,

 A.C. was habitually experimenting with drugs, including marijuana, cocaine,

 Xanax, and Klonopin, and drinking alcohol almost daily. These addictions

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 escalated during A.C.’s high school years, leading to an overdose in December

 2015.

         The overdose was a tipping point for A.C. Dr. Peacock attested that

 A.C.’s “pattern of behavior was growing more and more dangerous,” making

 inpatient treatment the only viable option. Id. at 52, 53. And so, given A.C.’s

 persistent recalcitrance and unwillingness to participate in therapy, Dr. Peacock

 recommended to Ian C. and his wife that they admit A.C. to an inpatient

 wilderness program.

         A.C. began treatment at one such program, Blue Fire Wilderness, on

 April 7, 2016. He was admitted for “Attention-Deficit/Hyperactivity Disorder,”

 “Alcohol Use Disorder,” and “Unspecified Depressive Disorder.” Id. at 56. At

 Blue Fire, A.C. participated in group therapy sessions, which sometimes

 focused on drug use and addiction. Halfway through A.C.’s stay at Blue Fire,

 Dr. Jeremy Chiles conducted a psychological evaluation of A.C. Regarding

 A.C.’s substance-use history, Dr. Chiles noted that A.C. began drinking alcohol

 at fourteen, which devolved into daily alcohol use by his junior year in high

 school. 3 His evaluation states that A.C. had experimented with a slew of other

 drugs, including marijuana, LSD, Xanax, cocaine, codeine, hydrocodone, and

 mushrooms. Id. at 96. Dr. Chiles portrayed A.C.’s drug use as a coping

         3
         Dr. Chiles stressed that “since [A.C.] was interviewed, he disclosed to
 his therapist at [Blue Fire] that his substance use involved the use of more
 drugs and was more regular than previously reported.” App. vol. 3, at 96. When
 admitted to Catalyst, A.C. reported that he first used alcohol at age twelve.
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 mechanism for his mental-health struggles and stated that “[i]n spite of

 resolutions to change, [A.C.] is likely to act out again in the future.” Id. at 102–

 03. Dr. Chiles diagnosed A.C. with “moderate to severe” cannabis use disorder

 and “moderate to severe” alcohol use disorder. Id. at 106. Because of that

 diagnosis, he “strongly recommended” that A.C. continue treatment at an

 inpatient residential facility with access to substance-use treatment. A.C. was

 discharged from Blue Fire on June 23, 2016.

       The next day, A.C. was admitted to Catalyst. Catalyst’s treatment plan

 listed five diagnoses as reasons for A.C.’s admission: (1) “Generalized anxiety

 disorder,” (2) “Unspecified depressive disorder,” (3) “Cannabis use disorder,”

 (4) “Parent-child relational problems,” and (5) “Alcohol use disorder.” App.

 vol. 4, at 43. Though A.C. had been drug- and alcohol-free for eleven weeks

 when he arrived at Catalyst, due to his preceding stay at Blue Fire, Catalyst

 classified his cannabis use disorder and alcohol use disorder as “severe.” Id. As

 a general requirement for A.C.’s treatment, Catalyst’s plan stated that A.C.

 needed “a place where he can have a sustained amount of time in sobriety as his

 drug use was severe and daily.” Id. The plan then laid out specific treatment

 goals related to A.C.’s cannabis use disorder. One goal was for A.C. to

 “demonstrate a clear understanding of the dynamics of substance dependence as

 they relate personally to [him].” Id. at 47. Another goal was for A.C. “to

 routinely identify situations and other factors that could pose a risk to [his]

 sobriety.” Id.

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       To fulfill these treatment goals, Catalyst prescribed A.C. individual and

 group therapy, on top of providing him an environment away from drugs and

 alcohol. Catalyst’s medical records show that A.C. completed this therapy, as

 directed by the treatment plan. During his treatment at Catalyst, A.C.

 experienced substance cravings and reported having “flashbacks of drinking.”

 App. vol. 6, at 46.

       C.     United’s Coverage

       On June 24, 2016, the date of A.C.’s admission to Catalyst, Ian C.

 submitted a request for coverage to United. In response, United completed an

 “Initial Facility-Based Review,” to determine A.C.’s eligibility for benefits.

 App. vol. 7, at 189. United’s intake form states that, though substance abuse

 was not a “primary driver” for A.C.’s admission to Catalyst, the “precipitant”

 for his admission was a “risk for relapse on drugs and alcohol” and

 “[i]nadequate relapse prevention strategies.” Id. at 192, 193. And the form

 specifies that A.C. was admitted to treat his use of alcohol, Xanax, cannabis,

 and cocaine. Id. at 194. The intake lists “Generalized anxiety d/o” as A.C.’s

 primary diagnosis, and lists “Persistent depressive d/o,” “Oppositional defiant

 d/o,” “Alcohol use d/o,” “Cannabis use d/o,” and “Attention-

 deficient/hyperactivity” as additional diagnoses. Id. at 191. Noting these

 collective diagnoses and applying the Mental Health Guidelines, United

 approved benefits for A.C. to receive four days of residential treatment at

 Catalyst.

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       After the initial four days elapsed, United revisited A.C.’s eligibility.

 Upon review, United approved A.C. for four additional days at Catalyst

 because his symptoms were “not manageable in a less restrictive setting.” Id.

 at 203–04. United documented A.C.’s mental state as “anxious, restless,

 irritable, depressed,” and “sad,” and added that A.C. was “having high cravings

 for using.” Id. at 204. Four days later, United conducted another review and

 authorized another three days of coverage. This time, United reported that A.C.

 was experiencing “craving for substances,” feeling “anxious,” “depressed,”

 “isolat[ed],” and suffering visual hallucinations. 4 Id. at 213. Three days later,

 United reassessed A.C.’s condition and his eligibility yet again. United found

 that A.C. was “restless,” “telling therapist[s] what they want[ed] to hear,” and

 “professing sobriety despite [his] long [history] of drug use,” which led United

 to conclude that A.C.’s symptoms, once again, could not be treated in a “less

 restrictive setting.” Id. at 219, 221.

       This litany of short-lived extensions brings us to July 7, 2016. By that

 time, A.C. had received two weeks of treatment at Catalyst, which United

 covered. Then, Ian C. requested United to cover another thirty days. This time,

       4
         United’s internal notes for this extension show that the reviewer used
 the “LOC SA Residential rehabilitation” guidelines to evaluate A.C.’s
 eligibility for benefits. App. vol. 7, at 214. This notation indicates that the
 reviewer used the “level of care” guidelines for “substance abuse” to assess
 coverage, which differs from all the other reviews that used the “LOC MH
 Residential treatment” guidelines, or rather, the Mental Health Guidelines. E.g.,
 id. at 28, 197, 205, 222. United’s one-time use of the Substance Abuse
 Guidelines is not mentioned by either party, so we will not discuss it further.
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  United declined the request. In fact, United not only rejected Ian C.’s request

  for a thirty-day extension, but it also denied coverage for A.C.’s residential

  treatment moving forward and recommended that he be discharged to intensive

  outpatient therapy. United based this decision on the Mental Health Guidelines,

  determining that “the treatment being recommended” for A.C.’s general anxiety

  disorder did “not appear to be consistent with generally accepted standards of

  medical practice.” Id. at 233. United’s internal-review notes accompanying its

  recommendation show that A.C. was still reporting cravings and had

  experienced a “flash back of drinking” two days earlier that “triggered him.”

  Id. at 230.

        D.      Level One Denial

        United sent its decision to deny coverage to a peer reviewer, Dr. Sheryl

  Jones, to corroborate or challenge its determination. To assess the claim, Dr.

  Jones reviewed United’s internal notes on A.C.’s case, called “Linx Case

  Notes,” and interviewed a designee from Catalyst. Using this information and

  applying the Mental Health Guidelines, Dr. Jones affirmed United’s adverse

  benefit determination. She found that A.C.’s continued treatment at Catalyst

  was not covered by the plan because his treatment no longer met the “Medical

  Necessity Criteria.” Id. at 238–39. This decision became effective July 8, 2016.

        Dr. Jones sent a letter to Ian C. notifying him that A.C.’s benefits from

  July 8, 2016 forward had been denied. See 29 U.S.C. § 1133(1). This letter,

  dated July 12, 2016, provides that “[a]fter speaking with the facility designee,

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  it seems that your child has made progress and that his condition no longer

  meets guidelines for coverage of treatment in this setting.” App. vol. 3, at 23.

  Though Dr. Jones acknowledged that A.C. was admitted partially for “treatment

  of substance use,” she expounded that A.C. did “not have serious withdrawal or

  post-acute withdrawal symptoms” that would justify continued coverage. Id.

        E.     Level Two Denial

        After receiving Dr. Jones’s letter, Ian C. invoked his right to appeal

  under the plan. He authored a “Level One Member Appeal,” dated January 4,

  2017, challenging Dr. Jones’s decision on several grounds. Id. at 4–17. Most

  saliently, he argued that Dr. Jones neglected to apply the Substance Abuse

  Guidelines along with the Mental Health Guidelines. He also accused Dr.

  Jones’s letter of violating ERISA regulations, which require plan administrators

  to furnish “specific references in the medical records relied upon in reaching

  their conclusion.” Id. at 7, 8.

        Ian C.’s appeal stressed the severity of A.C.’s substance abuse and

  attested that outpatient therapy had been powerless to treat A.C.’s addictions in

  the past. He urged the next reviewer to reassess A.C.’s claim under the

  Substance Abuse Guidelines, which supported his position that A.C. was not

  ready to be discharged from an inpatient facility. Ian C. provided the next

  reviewer with several documents to consider with his appeal. He included in the

  body of his appeal an excerpted reference letter from Dr. Peacock, A.C.’s child

  psychologist, and excerpted medical records from Catalyst. Attached to the

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  appeal letter, Ian C. appended A.C.’s medical records from Blue Fire, a

  medication disclosure form, Dr. Chiles’s evaluation, and more medical records

  from Catalyst.

        United assigned Dr. Cheryl Person to conduct the second review of

  Ian C.’s claim. According to the plan, Dr. Person was a licensed psychiatrist

  who was uninvolved in the initial adverse benefit determination. After

  reviewing Ian C.’s “appeal letter, case notes, medical records and [the Mental

  Health Guidelines],” Dr. Person upheld Dr. Jones’s denial of benefits. App.

  vol. 7, at 42.

        Dr. Person officially communicated her decision to Ian C. in a denial

  letter dated January 19, 2017. 5 The letter explained that because A.C. “had

  made progress,” “was not endangering the welfare of himself or others,” “was

  attending and participating in programming,” and “was tapered off his

  antidepressants as his mood was stable,” he no longer met the criteria for

  coverage under the Mental Health Guidelines. Id. at 42–43. Dr. Person noted

  that A.C. was admitted to Catalyst for “General Anxiety Disorder,” without

  mentioning his substance-abuse-related diagnoses. Id. at 42. She identified

  A.C.’s “remaining symptoms,” as “parental-child conflict,” which she deduced

  could be treated “in a less restrictive setting.” Id. at 43.

        5
           A.C.’s provider notified United that it did not receive Dr. Person’s
  letter, and so United issued a second copy dated March 31, 2017. There is no
  substantive difference between the two versions.
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         Upon receiving Dr. Person’s letter, Ian C. had exhausted the internal

  appeals process available to him under the plan. And so, he invoked his right to

  sue United in federal district court. See 29 U.S.C. § 1132(a)(1)(B). 6

  II.    Procedural Background

         On July 5, 2019, Ian C. filed a complaint against United seeking

  (1) recovery of benefits under ERISA, 29 U.S.C. § 1132(a)(1)(B); and

  (2) injunctive relief. He voluntarily dismissed the second claim with prejudice

  in a stipulated motion. Ian C. and United then filed motions for summary

  judgment on the ERISA claim. On August 11, 2022, the district court granted

  summary judgment for United and entered judgment the same day. This timely

  appeal followed.

  III.   Standard of Review

         A.    Summary Judgment

         “Where, as here, the parties in an ERISA case both moved for summary

  judgment, summary judgment is merely a vehicle for deciding the case; the

  factual determination of eligibility for benefits is decided solely on the

  administrative record, and the nonmoving party is not entitled to the usual

  inferences in its favor.” Carlile v. Reliance Standard Life Ins. Co., 988 F.3d

  1217, 1221 (10th Cir. 2021) (cleaned up).

         6
          Section 1132(a)(1)(B) empowers a plan participant to bring a civil
  action against the plan administrator “to recover benefits due to him under the
  terms of his plan” or “to enforce his rights under the terms of the plan.”
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         Because the parties dispute the proper standard of review, we address

  that issue first.

         B.     ERISA Review Standards

         Typically, we review motions for summary judgment de novo. Nat’l

  Union Fire Ins. Co. of Pittsburgh v. Dish Network, LLC, 17 F.4th 22, 29

  (10th Cir. 2021). But ERISA cases are a horse of a different color. In the

  ERISA context, we proceed de novo unless the plan authorizes the

  administrator to determine benefits on a discretionary basis, in which case we

  apply the more deferential arbitrary-and-capricious review standard. See

  Firestone Tire & Rubber Co. v. Bruch, 489 U.S. 101, 115 (1989) (establishing

  the standard of review for § 1132(a)(1)(B) appeals).

         Ian C.’s plan grants United authority to interpret the terms of the plan

  and make discretionary benefits decisions. This would suggest arbitrary-and-

  capricious review. See Eugene S. v. Horizon Blue Cross Blue Shield of N.J.,

  663 F.3d 1124, 1131 (10th Cir. 2011); Firestone, 489 U.S. at 115. But Ian C.

  argues that we should review his appeal de novo because United failed to

  “substantially comply” with ERISA’s procedural requirements. 7 See Hancock v.

         7
          The substantial-compliance rule was born out of a desire to avoid a
  “hair-trigger” rule that would divest plan administrators of their deference to
  make benefits decisions for trivial infractions of ERISA’s requirements. See
  LaAsmar v. Phelps Dodge Corp. Life, Accidental Death & Dismemberment &
  Dependent Life Ins. Plan, 605 F.3d 789, 799 (10th Cir. 2010); Finley v.
  Hewlett-Packard Co. Emp. Benefits Org. Income Protection Plan, 379 F.3d
  1168, 1173–74 (10th Cir. 2004). Instead, we withhold judicial deference only
                                                               (footnote continued)
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  Metro. Life Ins. Co., 590 F.3d 1141, 1152 (10th Cir. 2009) (“[D]e novo review

  may be appropriate if the benefit-determination process did not substantially

  comply with ERISA regulations . . . .”). And more broadly, owing to the

  Department of Labor’s 2002 and 2011 amendments to the ERISA regulations,

  Ian C. proposes that we adopt de novo review for all cases in which

  administrators fail to “strictly adhere[]” to ERISA regulations. Op. Br. at 15,

  16, 17, 19 (first quoting 29 C.F.R. § 2560.503-1(a) (“2002 regulations”); and

  then quoting 29 C.F.R. § 2590.715-2719(b)(2)(ii)(F)(1)-(2) (“2011

  regulations”)). United and the United States Chamber of Commerce, amicus

  curiae, argue that the default arbitrary-and-capricious review standard should

  remain. We agree.

        The Supreme Court created the default deferential-review standard for

  ERISA claims in Firestone, 489 U.S. at 115. The Court reasoned that judicial

  deference to decisions issued by plan administrators was appropriate because

  “ERISA abounds with the language and terminology of trust law,” which

  traditionally accords deference to the discretionary exercise of fiduciary duties.

  when administrators fail to show a “valid exercise” of their discretion.
  Gilbertson v. Allied Signal, Inc., 328 F.3d 625, 631 (10th Cir. 2003)
  (addressing the case when “the administrator’s ‘deemed denied’ decision is by
  operation of law rather than the exercise of discretion”). Otherwise,
  administrators are considered in “substantial compliance” with ERISA, and
  thus deserving of judicial deference. See id. at 636 (explaining that substantial
  compliance requires the administrator to be engaged in “an ongoing productive
  evidence-gathering process in which the claimant is kept reasonably well-
  informed”).
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  Id. at 110–11. The Court has faced multiple opportunities to overturn or

  otherwise tweak Firestone deference; and in every instance, it has declined.

  See, e.g., Conkright v. Frommert, 559 U.S. 506, 517 (2010) (reaffirming the

  role Firestone deference plays in preserving ERISA’s “careful balancing”

  between beneficiaries’ rights and administrators’ interests (quoting Aetna

  Health Inc. v. Davila, 542 U.S. 200, 215 (2004))); Metro Life Ins. Co. v. Glenn,

  554 U.S. 105, 115 (2008) (reexamining and upholding Firestone deference even

  when the administrator had a conflict of interest). In fact, in Glenn, the Court

  expressly repudiated the prospect of “near universal review by judges de novo

  . . . of the lion’s share of ERISA plan claims denials.” 554 U.S. at 116.

        Nothing in Ian C.’s brief convinces us to stir the pot. 8 First and foremost,

  his argument assumes that the Department of Labor’s ERISA regulations can,

  or should, dictate our judicial standards of review. That is a flawed premise.

  Congress delegated authority to the Secretary of Labor to enact procedural

  regulations to enforce ERISA’s policies, but that authorizing legislation never

        8
          In Kellogg v. Metropolitan Life Insurance Co., we addressed a similar
  argument about the 2002 regulations’ impact on the substantial-compliance
  rule. 549 F.3d 818, 828 (10th Cir. 2008) (entertaining the idea that the 2002
  ERISA regulations “called into question the continuing validity of the
  substantial compliance rule”). But there, we declined to decide the issue
  because the administrator’s violation of ERISA deadlines was so egregious and
  blatant that there was “little doubt” the administrator had failed to comply with
  ERISA’s requirements, substantially or otherwise. See id.; see also Rasenack ex
  rel. Tribolet v. AIG Life Ins. Co., 585 F.3d 1311, 1316–17 (10th Cir. 2009)
  (declining to extend deference because AIG supplied no “good faith”
  justification for its repeated violations of ERISA-mandated deadlines).
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  mentioned judicial standards of review. See 29 U.S.C. § 1135 (authorizing the

  Secretary to “prescribe such regulations as he finds necessary or appropriate to

  carry out the provisions of this subchapter”). Congress intentionally left

  ERISA’s standard of review open to the judiciary’s interpretation, which the

  Supreme Court duly supplied in Firestone. See Glenn, 554 U.S. at 116

  (perceiving that Congress “left to the courts the development of review

  standards” for ERISA actions).

        Second and more practically, because United cannot surmount arbitrary-

  and-capricious review, it would be fruitless for us to proceed de novo. See, e.g.,

  David P. v. United Healthcare Ins. Co., 77 F.4th 1293, 1308 n.11 (10th Cir.

  2023) (dispensing with de novo review even when it was appropriate because

  “[United’s] adverse benefits determination fail[ed] . . . an arbitrary and

  capricious standard of review”). Thus, this case is not an appropriate vehicle

  for us to reevaluate our standard of review.

        C.    Arbitrary-and-Capricious Review

        Our review goes to the plan administrator’s decision, not the district

  court’s. See Foster v. PPG Indus., Inc., 693 F.3d 1226, 1231 (10th Cir. 2012)

  (quoting Holcomb v. Unum Life Ins. Co. of Am., 578 F.3d 1187, 1192 (10th Cir.

  2009)). We review the plan administrator’s decision for arbitrariness and

  capriciousness. Id.

        “Under arbitrary and capricious review, this court upholds [the

  administrator’s] determination so long as it was made on a reasoned basis and

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  supported by substantial evidence.” Van Steen v. Life Ins. Co. of N. Am.,

  878 F.3d 994, 997 (10th Cir. 2018); see Foster, 693 F.3d at 1231–32 (clarifying

  that, in the ERISA context, we treat “the abuse-of-discretion standard and the

  arbitrary-and-capricious standard as interchangeable” (cleaned up)).

  “Substantial evidence is such evidence that a reasonable mind might accept as

  adequate to support the conclusion reached by the decisionmaker.” Sandoval v.

  Aetna Life and Cas. Ins. Co., 967 F.2d 377, 382 (10th Cir. 1992) (cleaned up).

  And as we consider “whether the evidence in support of the administrator’s

  decision is substantial, we must take into account whatever in the record fairly

  detracts from its weight.” Graham v. Hartford Life & Accident Ins. Co., 589

  F.3d 1345, 1358 (10th Cir. 2009) (quoting Caldwell v. Life Ins. Co. of N. Am.,

  287 F.3d 1276, 1282 (10th Cir. 2002)).

        When issuing an adverse benefit determination, an administrator must

  provide the participant “adequate notice in writing . . . setting forth the specific

  reasons for such denial, written in a manner calculated to be understood by the

  participant.” 29 U.S.C. § 1133(1). After the administrator issues an adverse

  benefit determination, the participant is entitled to a “reasonable opportunity”

  for a “full and fair review” of the decision. Id. § 1133(2). A “full and fair

  review” discloses to the participant the “evidence the decision-maker relied

  upon.” D.K. v. United Behav. Health, 67 F.4th 1224, 1236 (10th Cir. 2023)

  (quoting Sage v. Automation, Inc. Pension Plan & Tr., 845 F.2d 885, 893–94

  (10th Cir. 1988)). Our review is limited to “those rationales that were

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  specifically articulated in the administrative record as the basis for denying a

  claim.” Spradley v. Owens-Illinois Hourly Empls. Welfare Benefit Plan,

  686 F.3d 1135, 1140 (10th Cir. 2012) (quoting Flinders v. Workforce

  Stabilization Plan of Phillips Petroleum Co., 491 F.3d 1180, 1190 (10th Cir.

  2007), overruled on other grounds by Glenn, 554 U.S. at 128, as recognized in

  Holcomb, 578 F.3d at 1192–93).

        Recently, in D.K. v. United Behavioral Health, we held that the

  administrator must include its reasons for denying coverage in the four corners

  of the denial letter. 67 F.4th at 1239 (“ERISA denial letters play a particular

  role in ensuring full and fair review. ERISA regulations require that denial

  letters be comprehensive and include . . . specific reasons for the denial.”

  (citing 29 C.F.R. § 2560.503-1(f)(3), (h)(3)–(4))). Under D.K., our analysis

  focuses on the two denial letters United furnished to Ian C., the first from Dr.

  Jones communicating the initial denial decision, but more critically the second

  from Dr. Person affirming the denial on appeal. 9

        9
          D.K. established that our review of an administrator’s benefits denial is
  confined to the denial letters. See 67 F.4th at 1239. Though United sent two
  denial letters, Dr. Person’s letter pulls focus because Ian C. appeals based on an
  independent-ground-for-coverage theory. After Ian C. received the initial denial
  from Dr. Jones, he specifically raised substance abuse as an independent ground
  for coverage for the next reviewer to consider. As the second reviewer, Dr.
  Person was uniquely positioned to respond to Ian C.’s appeal, and so her letter is
  all important.
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                                    DISCUSSION

        Ian C. argues that United’s denial of benefits for A.C.’s treatment at

  Catalyst, effective July 8, 2016, was arbitrary and capricious because United

  overlooked A.C.’s substance abuse as an independent ground for coverage.

  Ian C. challenges United’s view that A.C.’s substance abuse was in any way

  “secondary” to his mental-health condition. Op. Br. at 27. According to Ian C.,

  substance abuse was central to A.C.’s treatment, and therefore, United needed

  to address that portion of his condition when it denied benefits. Ian C.

  additionally rejects United’s citations to its internal notes, peer reviews, and

  other portions of the record to support its argument that A.C.’s substance abuse

  was taken into account during the review process. He maintains that United

  cannot “paper over the deficiencies in its denial letters” with reasoning and

  citations to parts of the record that it never communicated to him. Id. at 26.

  I.    Independent Ground for Coverage

        Ian C.’s main argument on appeal is that United disregarded A.C.’s

  substance abuse as an independent ground for coverage under the plan. This

  court addressed the independent-ground-for-coverage theory most notably in

  Gaither v. Aetna Life Ins. Co., 394 F.3d 792 (10th Cir. 2004). Gaither

  examined the case of a man caught in a Catch-22: the prescription painkillers

  he took to manage severe chronic pain made him unable to work, according to

  his employer, and at the same time ineligible to receive disability benefits,

  according to his health plan administrator. Id. at 798, 799. Gaither insisted that

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  his reliance on the painkillers prevented him from performing his job, and thus

  that he qualified for disability benefits. Id. at 800. He appealed the

  administrator’s denial of benefits to that effect. Id. But the administrator

  reaffirmed the denial based on Gaither’s failure to prove that he suffered from a

  psychological anxiety disorder, meanwhile “overlook[ing] [his] signs of a

  potential drug use problem.” Id. at 802.

        We observed that Gaither had “specifically raised” his use of painkillers

  as “another independent ground for disability,” and that the administrator “did

  not have substantial evidence about the extent or effects” of his drug use

  sufficient to contradict his claim. Id. at 806. Yet the administrator denied

  coverage without considering Gaither’s drug use as an independent ground for

  coverage. Id. And so, we held that the administrator acted arbitrarily and

  capriciously by shutting its eyes to evidence that supported Gaither’s “theory of

  entitlement.” Id. at 807 (“[W]e assert the narrow principle that fiduciaries

  cannot shut their eyes to readily available information when the evidence in the

  record suggests that the information might confirm the beneficiary’s theory of

  entitlement and when they have little or no evidence in the record to refute that

  theory.”). From a policy perspective, we emphasized that administrators, as

  fiduciaries, have a “duty to see that those entitled to benefits receive them.” Id.

  at 807–08. This process requires a “meaningful dialogue” between both parties

  to unearth all the relevant evidence surrounding the participant’s claim and to

  guarantee that benefits are distributed according to the plan. Id. at 807 (quoting

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  Gilbertson, 328 F.3d at 635). Finding the administrator’s cooperation in those

  efforts lacking, we reversed the district court’s decision that the administrator’s

  denial wasn’t arbitrary and capricious. Id. at 809.

        Similarly, in David P. v. United Healthcare Insurance Co., we affirmed

  the district court’s ruling against United because United overlooked the

  beneficiary’s substance abuse as an independent ground for coverage separate

  from her mental-health treatment at a residential treatment center. 10 77 F.4th

  at 1309 (citing Gaither, 394 F.3d at 806). Not only was there evidence in the

  record that the patient had been receiving treatment for both conditions, but the

  administrative appeal specifically identified substance-abuse treatment as an

  independent ground for coverage. Id. at 1310. Despite having raised the issue,

  United neglected to address substance abuse in its ultimate adverse benefits

  determination. Id. (concluding that the reviewer’s passing reference to

  “addiction” was not enough because “even then that reviewer did not separately

  state why [the beneficiary’s] substance abuse treatment did not warrant

  coverage”). Based on that omission, we affirmed the district court’s decision

  against United. Id. at 1316–17.

        Here, after Dr. Jones initially denied benefits for A.C.’s treatment at

  Catalyst as of July 8, 2016, Ian C. appealed. In his appeal, Ian C. faulted Dr.

        10
           Ian C. filed a Federal Rule of Appellate Procedure 28(j) letter alerting
  this court to David P.’s issuance. The letter asserted that David P. offered
  additional support for the argument that United cannot rely on its internal notes
  to justify the benefits denial.
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  Jones for evaluating A.C. solely under the Mental Health Guidelines without

  considering the Substance Abuse Guidelines too. He insisted that United’s

  review needed to apply this “dual criteria” because A.C. was “dually

  diagnosed.” App. vol. 3, at 5, 6. His letter expressed concern that A.C.’s

  “release from treatment would assuredly lead to relapse” because A.C.’s

  residence at Catalyst was the only thing keeping him sober. Id. at 7. And to

  support these claims, Ian C. appended a bevy of evidence for the second

  reviewer to consider with his appeal, including the Substance Abuse

  Guidelines.

        But Dr. Person affirmed Dr. Jones’s adverse benefit determination

  without mentioning any of the evidence or arguments that Ian C. raised. Citing

  the Mental Health Guidelines, Dr. Person denied benefits because A.C.’s

  “General anxiety disorder” no longer required “24-hour nursing care or

  supervision provided at this level of care” and because he had “made progress.”

  App. vol. 7, at 42, 43. She listed A.C.’s only remaining symptom as “parent-

  child conflict,” which she determined was treatable in a “less restrictive

  setting.” Id. at 43. Dr. Person’s denial letter made no substantive mention of

  A.C.’s substance abuse, the Substance Abuse Guidelines, or the evidence Ian C.

  submitted with his appeal. Ian C. contends that Dr. Person’s denial was

  arbitrary and capricious because she tacitly rejected A.C.’s substance abuse as

  an independent ground for coverage.

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        Arbitrary-and-capricious review of the administrator’s appeal process is

  not “without meaning.” McMillan v. AT&T Umbrella Benefit Plan No. 1,

  746 F. App’x 697, 705 (10th Cir. 2018) (unpublished). This court established in

  Gaither that, when reviewing adverse benefit determinations, the fiduciary

  must consider an independent ground for coverage that the claimant raises

  during the appeal. 394 F.3d at 807; see Black & Decker Disability Plan v. Nord,

  538 U.S. 822, 834 (2003) (“Plan administrators . . . may not arbitrarily refuse

  to credit a claimant’s reliable evidence . . . .”). To be sure, this rule applies

  only when the administrator has “little or no evidence in the record to refute”

  the claimant’s ground for recovery. Blair v. Alcatel-Licent Long Term

  Disability Plan, 688 F. App’x 568, 577 n.11 (10th Cir. 2017) (unpublished)

  (quoting Gaither, 394 F.3d at 807) (discussing “the Gaither rule”). But that is

  the case here.

        This record is replete with evidence of A.C.’s substance abuse and the

  treatment he received for it at Catalyst. Catalyst’s therapists noted that A.C.

  experienced “flashbacks of drinking” days before United cancelled coverage.

  App. vol. 6, at 46. The facility marked his cannabis use disorder and alcohol

  use disorder as “severe,” even though A.C. hadn’t used drugs or alcohol for

  weeks. App. vol. 4, at 43. Catalyst noted that A.C. needed to be somewhere he

  could enjoy “a sustained amount of time in sobriety” because his addictions

  were so severe. Id. Likewise, Dr. Chiles’s and Dr. Peacock’s accounts of A.C.’s

  substance-use history underscore the severity of A.C.’s addictions and recount

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  that his previous attempts at outpatient therapy were ineffective. And even

  United’s internal paperwork acknowledges that A.C. was at Catalyst to receive

  treatment for alcohol, Xanax, cannabis, and cocaine.

        On this record, United was not justified in shutting its eyes to the

  possibility that A.C. was entitled to benefits based on his substance abuse.

  Compare David P., 77 F.4th at 1310 (noting that “it was clear from the record

  before” United that the claimant was being treated for substance abuse);

  Harrison v. Wells Fargo Bank, N.A., 773 F.3d 15, 23 (4th Cir. 2014)

  (concluding that because “the record did not refute [the claimant’s] claim of

  disability” and the claimant presented “a close case” for recovery, the

  administrator’s denial was arbitrary and capricious), with Roganti v. Metro.

  Life Ins. Co., 786 F.3d 201, 216 (2d Cir. 2015) (deciding that the

  administrator’s denial was not arbitrary and capricious because the claimant’s

  “evidence taken alone was inadequate to support his claim”); Rizzi v. Hartford

  Life & Accident Ins. Co., 383 F. App’x 738, 752 (10th Cir. 2010) (unpublished)

  (determining that the administrator was not required to consider the purported

  ground for coverage because the claimant failed to submit “any tangible

  evidence” supporting the claim). And so, we agree that Dr. Person’s complete

  erasure of A.C.’s substance abuse, after Ian C. specifically raised it as an

  independent ground for coverage in his appeal, was arbitrary and capricious.

        United attempts to distinguish this case from Gaither by claiming it

  followed up on “obvious leads” pointing to A.C.’s substance abuse through its

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  conversations with Catalyst staff. Resp. Br. at 52–53. United contends that

  despite the evidence acquired from those inquiries, the reviewers concluded

  A.C.’s continued treatment at Catalyst was not “medically necessary.” Id. at 53.

  This argument misplaces Gaither in the canon of ERISA-benefits-denial cases.

  Gaither dealt with independent grounds for coverage, not medical necessity. 11

  See 395 F.3d at 806. Our focus is on the independent ground for coverage. If an

  administrator’s decision ignores an independent ground for coverage and there

  is scant evidence to refute the claimant’s theory, then the decision fails

  arbitrary-and-capricious review. See id. (determining that the administrator

  “rejected [Gaither’s] claim without a substantial basis for doing so” because it

  “did not have substantial evidence” about the condition that provided his

  independent ground for coverage); David P., 77 F.4th at 1310 (reversing the

  denial of coverage because United “fail[ed] to address [the beneficiary’s]

  substance abuse treatment as an independent ground for coverage” even though

  her receipt of such treatment was “clear from the record”).

        11
           In his opening brief to this court, Ian C. stipulates that “[b]ecause the
  district court’s decision cannot stand,” he does not address the arguments he
  made before the district court “that A.C.’s treatment at Catalyst was medically
  necessary, that United abused its discretion by not engaging with A.C.’s treating
  professionals’ opinions and not articulating how it applied the terms of the Plan
  and internal guidelines to A.C.’s medical history.” Op. Br. at 13 n.4. Neither does
  he “address these rulings on appeal.” Id.
         In district court, Ian C.’s argument about medical necessity was that
  United had failed to consider A.C.’s medical records and medical history. See
  App. vol. 1, at 113–18. His waiver of that argument does not prevent him from
  arguing here (as he does) that United overlooked A.C.’s substance abuse as an
  independent ground for coverage.
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  II.   ERISA

        This result tracks ERISA’s statutes and regulations. See 29 U.S.C.

  § 1133; 29 C.F.R. § 2560.503-1(h)(2)(iv). Under ERISA, after the administrator

  issues an adverse benefit determination, the claimant is entitled to a “full and

  fair review by the appropriate named fiduciary.” Section 1133(2). This review

  must include a “meaningful dialogue” between the claimant and the

  administrator, which requires “an ongoing, good faith exchange of information”

  to ensure that the terms of the plan are applied accurately and the benefits are

  dispensed fairly. Gilbertson, 328 F.3d at 635; see Gaither, 394 F.3d at 807–08

  (“While a fiduciary has a duty to protect the plan’s assets against spurious

  claims, it also has a duty to see that those entitled to benefits receive them.”).

  A “good faith exchange of information” presumes that the administrator will

  consider any relevant evidence in the shared record between the parties that

  supports the claimant’s receiving benefits. Gilbertson, 328 F.3d at 635; see

  Rekstad v. U.S. Bancorp, 451 F.3d 1114, 1120 (10th Cir. 2006) (requiring that

  administrators reviewing a benefits denial “take into account whatever in the

  record fairly detracts from [the decision’s] weight” (quoting Caldwell, 287 F.3d

  at 1282)); Metzger v. UNUM Life Ins. Co. of Am., 476 F.3d 1161, 1167 (10th

  Cir. 2007) (recognizing that ERISA appeals may only “analyze evidence

  already known to the claimant”).

        To guarantee a “full and fair review” on appeal, the administrator must

  reevaluate the claim on a clean slate. ERISA regulations prohibit the second

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  reviewer from showing any deference to the first reviewer—a rare case when

  the appealing party gets a true second bite at the apple. 29 C.F.R. § 2560.503-

  1(h)(3)(ii). And the second reviewer must “take[] into account all comments,

  documents, records, and other information submitted by the claimant relating to

  the claim,” even if those materials were unavailable to the first reviewer. Id.

  § 2560.503-1(h)(2)(iv). This scheme holds the administrator accountable to

  interpret the plan “solely in the interest of the participants and beneficiaries.”

  29 U.S.C. § 1104(a)(1)(A)(i); see Rasenack, 585 F.3d at 1324 (“An ERISA

  fiduciary presented with a claim that a little more evidence may prove valid

  should seek to get to the truth of the matter.” (citation omitted)); Teets v.

  Great-West Life & Annuity Ins. Co., 921 F.3d 1200, 1206–07 (10th Cir. 2019)

  (clarifying that fiduciary obligations trigger when the fiduciary exercises their

  discretionary authority); Hennen v. Metro. Life Ins. Co., 904 F.3d 532, 541

  (7th Cir. 2018) (emphasizing that the administrator’s interpreting benefits

  under the plan constitutes “a fiduciary act” (citation omitted)).

        At minimum, Dr. Person was required to address Ian C.’s arguments and

  evidence of A.C.’s substance abuse, the Substance Abuse Guidelines, and the

  relevant provisions of the plan to provide a “full and fair review.” See

  29 C.F.R. § 2560.503-1(h)(2)(iv) (requiring the administrator to “[p]rovide for

  a review that takes into account all comments, documents, records, and other

  information admitted by the claimant relating to the claims”); see, e.g.,

  Hancock, 590 F.3d at 1154 (holding that MetLife’s denial letter satisfied “full

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  and fair review” because it cited the relevant plan provision, “summarized

  MetLife’s reasons for denying the claim and the first appeal,” and then

  explained that the claimant’s evidence “did not demonstrate with certainty” her

  stated grounds for recovery). But her letter is silent on A.C.’s substance abuse.

  By obscuring A.C.’s substance abuse and focusing solely on his mental-health

  treatment, United failed to “take[] into account all . . . information submitted

  by the claimant,” in violation of ERISA. 29 C.F.R. § 2560.503-1(h)(2)(iv). In

  doing so, United rebuffed its fiduciary duties and denied Ian C. his right to a

  “full and fair review.” See 29 U.S.C. §§ 1133(2), 1104(a)(1).

  III.   United’s Remaining Arguments 12

         United argues that Dr. Person didn’t need to address substance abuse in

  her denial letter because substance abuse was not a “primary driver” for A.C.’s

  admission to Catalyst. Resp. Br. at 45 (citing App. vol. 7, at 199, 208, 216,

  225). United’s emphasizing the “primary driver” for A.C.’s admission is an

  invention of creative lawyering. We have never used this language or placed

  any weight on the “primary driver” for a beneficiary’s treatment. Whether

  substance abuse was a predominant or subordinate factor to A.C.’s admission is

  irrelevant, so long as it could have served as an independent ground for

         12
          Our caselaw instructs us to reject many of the arguments that United
  makes on appeal because United did not rely on them in its denial letters to
  Ian C. See D.K., 67 F.4th at 1239; Spradley, 686 F.3d at 1140. But for
  completeness, we review each one in turn. As it happens, none of these
  arguments would change our decision.
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  coverage. See Gaither, 394 F.3d at 806. And we know that it could have

  because Ian C.’s plan covers services for substance-abuse treatment at

  residential treatment facilities like Catalyst. At any rate, United’s “primary

  driver” argument is overstated because United’s reviewers listed the “risk for

  relapse on drugs and alcohol” as the “precipitant” for his admission, which is

  hardly distinguishable from the “primary driver.”

        United next argues that Catalyst was not “actively treat[ing]” A.C. for

  substance abuse. Id. at 47. The record belies this assertion. Catalyst diagnosed

  A.C. with “severe” alcohol use disorder and cannabis use disorder as two of the

  five causes for his admission. App. vol. 4, at 43. It also prescribed individual

  and group therapy to treat A.C.’s cannabis use disorder, which the evidence

  shows he completed. But most of all, A.C.’s residence at Catalyst was itself

  part of the treatment because A.C. required “a place where he can have a

  sustained amount of time in sobriety as his drug use was severe and daily.” Id.

  United’s claim is disingenuous because its own notes from reviewing A.C.’s

  benefits eligibility repeatedly mark, “Yes,” next to the question asking whether

  A.C. was, “Admitted to treat this substance?”—referring to alcohol, Xanax,

  cannabis, and cocaine. E.g., App. vol. 7, at 194, 200, 209. Thus, United’s

  records undermine its own argument.

        United also claims that continued coverage for A.C.’s treatment at

  Catalyst was not medically necessary because he was not experiencing

  symptoms of withdrawal. United argues that Catalyst is “not a 12 step program”

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  and A.C.’s medical records lacked toxicology reports or drug monitoring,

  demonstrating that Catalyst was “not actively treat[ing]” A.C. for substance

  abuse. 13 Resp. Br. at 47. These points are unavailing. This court is not a

  treatment expert; Catalyst is the expert. Catalyst created an individualized plan

  to treat A.C.’s severe cannabis use disorder, and the evidence shows that the

  plan was followed. We have no reason but to conclude that Catalyst was

  treating A.C. for substance abuse when United revoked coverage on July 8,

  2016.

          Next, United maintains that Dr. Person’s evaluation of A.C. under the

  Mental Health Guidelines was sufficient without equal consideration of the

  Substance Abuse Guidelines. United contends that both Guidelines contain

  “nearly identical requirements,” making a dual review superfluous. Id. at 62.

  United reminds us that the plan covers only “medically necessary” services,

  adding that those services do not distinguish between mental-health and

  substance-use treatments.

          We disagree that the Mental Health Guidelines and Substance Abuse

  Guidelines are “nearly identical.” Though both Guidelines require the reviewer

  to consider “[c]o-occurring behavioral health and medical conditions,” the

          13
            Though Catalyst is not a 12-step program, we observe that A.C.’s
  residence there implicitly prevented him from using drugs or alcohol. Also,
  A.C.’s parents were referred to “Al Anon,” a program for family members of
  those suffering from alcohol addiction. App. vol. 7, at 237; see A L -A NON F AM .
  G RPS ., https://perma.cc/AL57-5WK3.
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  Substance Abuse Guidelines go one step further. Substance Abuse Guidelines

  section 1.3.1 states that administrators should consider the risk of relapse

  before discharge, specifically when “[a] co-occurring mental health condition is

  stabilizing but the remaining signs and symptoms are likely to undermine

  treatment in a less intensive setting.” App. vol. 3, at 43 (emphasis added). This

  provision militates against discharging a patient with substance abuse if the

  relapse risk is high, even when the patient’s mental health is improving. By

  disregarding this provision of the Substance Abuse Guidelines, Dr. Person

  ignored the possibility that outpatient treatment would expose A.C. to a greater

  risk of relapse despite his other “progress.” App. vol. 7, at 32. Ian C. flagged

  this concern in his appeal letter, bolstered by Dr. Peacock’s letter and Dr.

  Chiles’s psychological evaluation, and yet Dr. Person ignored it. App. vol. 3,

  at 7 (urging that A.C.’s “release from treatment would assuredly lead to

  relapse”).

        Even worse, the one remaining symptom Dr. Person identified for A.C.

  was “parent-child conflict.” App. vol. 7, at 32. She calculated that this could be

  treated adequately in a “less restrictive setting.” Id. But Dr. Chiles’s evaluation

  tethered A.C.’s “maladaptive pattern of alcohol and other drug use” directly to

  A.C.’s perceived “conflict within his home” and his tumultuous relationship

  with his parents. App. vol. 3, at 102. Not only was A.C.’s relationship with his

  parents a trigger for his drug use, but the record also contained evidence that

  A.C. sometimes used drugs with his sister, who was a regular user herself. If

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  Dr. Person had considered this evidence under the Substance Abuse Guidelines,

  particularly section 1.3.1, then she may have been dissuaded from discharging

  A.C. into his home environment where he faced a heightened risk of relapse.

        United rejoins that Ian C. bore the burden to prove A.C.’s entitlement to

  receive benefits under the Substance Abuse Guidelines and alleges that he

  failed to carry his burden. Because Ian C. never explains how the Substance

  Abuse Guidelines justify A.C.’s receiving benefits, United avows that the

  Guidelines cannot serve as the basis for us overturning the district court’s

  decision. In support, United cites a single district court case, Daniel B. v.

  United Healthcare, No. 2:20-CV-00606, 2022 WL 4484622, at *13 (D. Utah

  Sept. 27, 2022) (unpublished). We are not bound by Daniel B., and regardless

  we find it distinguishable because substance abuse was not a listed reason for

  the patient’s admission to treatment, unlike this case. See id. In Daniel B., the

  district court found that the patient was ineligible for benefits under the

  administrator’s substance-related guidelines. Id. But here, our review of the

  record and the Substance Abuse Guidelines leads us to conclude that A.C.

  likely would have been eligible for benefits had Dr. Person faithfully applied

  the appropriate guidelines.

        Finally, United insists that its reviewers’ internal notes are properly a

  part of the administrative record for Ian C.’s claim. Our recent disposition in

  D.K. forecloses this argument. 67 F.4th at 1243 (“Review of the information

  provided to claimant may be appropriately limited to the denial letters.”). Only

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  the rationales articulated to the beneficiary in the denial letter are eligible for

  review, both in the administrative appeal and before this court. See id. And

  though this litigation began before D.K.’s publication, our previous holdings

  put United on notice of this standard. 14 See Spradley, 686 F.3d at 1140 (“[T]he

  federal courts will consider only those rationales that were specifically

  articulated in the administrative record as the basis for denying a claim.”

  (cleaned up)); Flinders, 491 F.3d at 1190 (same); see also Sandoval, 967 F.2d

  at 380 (reasoning that to allow the district court to review evidence that was not

  presented to both parties during the decision-making process would “seriously

  impair” the “primary goal of ERISA” to expeditiously resolve benefits disputes

  (quoting Perry v. Simplicity Eng’g, 900 F.2d 963, 967 (6th Cir. 1990))). United

  cannot avail itself of its peer-to-peer conversations with Catalyst staff, Linx

  case notes, and the like to defend its decision because these materials were not

  conveyed to Ian C. in the denial letters. 15 See David P., 77 F.4th at 1313; D.K.,

  67 F.4th at 1243.

        14
            Ian C. filed a Rule 28(j) letter alerting this court to the newly issued
  D.K. opinion.
         15
            United mischaracterizes the issue by claiming that we routinely rely on
  administrators’ internal notes to uphold adverse benefit determinations, citing
  as an example Tracy O. v. Anthem Blue Cross Life and Health Insurance,
  807 F. App’x 845, 854–55 (10th Cir. 2020). The point is not whether courts
  refer to administrators’ internal records when deciding these cases. Rather, the
  concern is whether administrators rely on internal records and evidence to make
  benefits determinations and then withhold those reasonings from claimants. Our
  caselaw and ERISA regulations proscribe this practice. See 29 C.F.R.
  § 2560.503-1(g)(1)(i)–(iii) (requiring the initial denial letter to include “[t]he
                                                                    (footnote continued)
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Appellate Case: 22-4082   Document: 010110963219      Date Filed: 12/05/2023    Page: 35

        Therefore, none of United’s arguments dissuade us from concluding that

  it arbitrarily and capriciously denied A.C. benefits for his treatment at Catalyst

  and deprived Ian C. of his right to receive a “full and fair review” of his

  administrative appeal under 29 U.S.C. § 1133(2).

                                   CONCLUSION

        For these reasons, we reverse the district court’s finding that United’s

  decision was not arbitrary and capricious and remand the case for further

  consideration consistent with this opinion.

  specific reason or reasons for the adverse determination” and the “specific plan
  provision” the administrator used to make its decision); David P., 77 F.4th
  at 1313; D.K., 67 F.4th at 1242; Spradley, 686 F.3d at 1140.
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