The opinion of the court was delivered by: Suzanne H. Segal United States Magistrate Judge
MEMORANDUM DECISION AND ORDER
Plaintiff Jerina Traister ("Plaintiff") brings this action seeking to overturn the decision of the Commissioner of the Social Security Administration (hereinafter the "Commissioner" or the "Agency") denying her application for Supplemental Security Income ("SSI") benefits. Alternatively, she asks for a remand. The parties consented, pursuant to 28 U.S.C. § 636(c), to the jurisdiction of the undersigned United States Magistrate Judge. The parties filed a Joint Stipulation ("JS"), pursuant to this Court's Case Management Order, in support of their respective positions. For the reasons stated below, the decision of the Commissioner is REVERSED and REMANDED for further administrative proceedings.
THE FIVE-STEP SEQUENTIAL EVALUATION PROCESS
To qualify for disability benefits, a claimant must demonstrate a medically determinable physical or mental impairment that prevents him from engaging in substantial*fn1 gainful activity and that is expected to result in death or to last for a continuous period of at least twelve months. Reddick v. Chater, 157 F.3d 715, 721 (9th Cir. 1998) (citing 42 U.S.C. § 423(d)(1)(A)). The impairment must render the claimant incapable of performing the work he previously performed and incapable of performing any other substantial gainful employment that exists in the national economy. Tackett v. Apfel, 180 F.3d 1094, 1098 (9th Cir. 1999) (citing 42 U.S.C. § 423(d)(2)(A)).
To decide if a claimant is entitled to benefits, an ALJ conducts a five-step inquiry. 20 C.F.R. §§ 404.1520, 416.920. The steps are:
(1) Is the claimant presently engaged in substantial gainful activity? If so, the claimant is found not disabled. If not, proceed to step two.
(2) Is the claimant's impairment severe? If not, the claimant is found not disabled. If so, proceed to step three.
(3) Does the claimant's impairment meet or equal one of list of specific impairments described in 20 C.F.R. Part 404, Subpart P, Appendix 1? If so, the claimant is found disabled. If not, proceed to step four.
(4) Is the claimant capable of performing his past work? If so, the claimant is found not disabled. If not, proceed to step five.
(5) Is the claimant able to do any other work? If not, the claimant is found disabled. If so, the claimant is found not disabled.
Tackett, 180 F.3d at 1098-99; see also Bustamante v. Massanari, 262 F.3d 949, 953-54 (9th Cir. 2001) (citing Tackett, 180 F.3d at 1098-99); 20 C.F.R. §§ 404.1520(b) - 404.1520(g)(1) & 416.920(b) - 416.920(g)(1).
The claimant has the burden of proof at steps one through four, and the Commissioner has the burden of proof at step five. Bustamante, 262
F.3d at 953-54 (citing Tackett, 180 F.3d at 1098). Additionally, the ALJ has an affirmative duty to assist the claimant in developing the record at every step of the inquiry. Id. at 954. If, at step four, the claimant meets his burden of establishing an inability to perform past work, the Commissioner must show that the claimant can perform some other work that exists in "significant numbers" in the national economy, taking into account the claimant's residual functional capacity ("RFC"),*fn2 age, education, and work experience. Tackett, 180 F.3d at 1098, 1100; Reddick, 157 F.3d at 721; 20 C.F.R. §§ 404.1520(g)(1), 416.920(g)(1). The Commissioner may do so by the testimony of a vocational expert or by reference to the Medical-Vocational Guidelines appearing in 20 C.F.R. Part 404, Subpart P, Appendix 2 (commonly known as "the Grids"). Osenbrock v. Apfel, 240 F.3d 1157, 1162 (9th Cir. 2001) (citing Tackett, 180 F.3d at 1100-01). When a claimant has both exertional ...