G. MURRAY SNOW, District Judge.
Pending before the Court is the appeal of Plaintiff Thomas William O'Connell, which challenges the Social Security Administration's decision to deny benefits. (Doc. 17.) For the reasons set forth below, the Court vacates the ALJ's decision and remands for further proceedings.
O'Connell applied for disability insurance benefits and for supplemental security income on June 22, 2009. (R. at 18.) In both applications, O'Connell alleged a disability onset date of May 20, 2009. ( Id. ) O'Connell met the insured status requirements of the Social Security Act through September 30, 2013. ( Id. ) His claims were denied both initially and upon reconsideration. ( Id. at 66-69, 1-6.) He then appealed to an Administrative Law Judge ("ALJ"). ( Id. at 7-14.) The ALJ conducted a hearing on the matter on October 17, 2011. ( Id. at 35-61.)
In evaluating whether O'Connell was disabled, the ALJ undertook the five-step sequential evaluation for determining disability. ( Id. at 25-26.) At step one, the ALJ determined that O'Connell had not engaged in substantial gainful activity since the alleged onset date. ( Id. at 20.) At step two, the ALJ determined that O'Connell suffered from the severe impairments of cirrhosis of the liver due to autoimmune hepatitis, chronic obstructive pulmonary disease, and obstructive sleep apnea with fatigue. ( Id. at 21.) At step three, the ALJ determined that none of these impairments, either alone or in combination, met or equaled any of the Social Security Administration's listed impairments. ( Id. at 24.)
At that point, the ALJ made a determination of O'Connell's residual functional capacity ("RFC"),  concluding that he could perform sedentary work with some limitations. ( Id. at 24-27.) The ALJ thus determined at step four that O'Connell retained the RFC to perform his past relevant work as a Customer Service Representative in a call center. ( Id. at 27.) The ALJ did not reach step five. Given this analysis, the ALJ concluded that O'Connell was not disabled. ( Id. at 28.)
The Appeals Council declined to review the decision. ( Id. at 1-6.)
Plaintiff filed the complaint underlying this action on December 18, 2012, seeking this Court's review of the ALJ's denial of benefits. (Doc. 1.) The matter is now fully briefed before this Court. (Docs. 17, 23, 29.)
I. STANDARD OF REVIEW
A reviewing federal court will only address the issues raised by the claimant in the appeal from the ALJ's decision. See Lewis v. Apfel, 236 F.3d 503, 517 n.13 (9th Cir. 2001). A federal court may set aside a denial of disability benefits only if that denial is either unsupported by substantial evidence or based on legal error. Thomas v. Barnhart, 278 F.3d 947, 954 (9th Cir. 2002). Substantial evidence is "more than a scintilla but less than a preponderance." Id. (quotation omitted). "Substantial evidence is relevant evidence which, considering the record as a whole, a reasonable person might accept as adequate to support a conclusion." Id. (quotation omitted).
However, the ALJ is responsible for resolving conflicts in testimony, determining credibility, and resolving ambiguities. See Andrews v. Shalala, 53 F.3d 1035, 1039 (9th Cir. 1995). "When the evidence before the ALJ is subject to more than one rational interpretation, we must defer to the ALJ's conclusion." Batson v. Comm'r of Soc. Sec. Admin., 359 F.3d 1190, 1198 (9th Cir. 2004). This is so because "[t]he [ALJ] and not the reviewing court must resolve conflicts in evidence, and if the evidence can support either outcome, the court may not substitute its judgment for that of the ALJ." Matney v. Sullivan, 981 F.2d 1016, 1019 (9th Cir. 1992) (citations omitted).
O'Connell argues that the ALJ erred by: (A) finding that O'Connell's impairments do not meet or equal a listed impairment without substantial evidence in the record at step three; (B) failing to properly weigh medical source opinion evidence; and (C) failing to properly weigh ...