In the case of Jo Anne B. Barnhart, Commissioner of Social Security v. Cleveland B. Walton, 2001, the U.S Supreme Court was asked to determine whether an administrative law judge (ALJ) is required to investigate a claimant's mental capacity before deciding on their disability benefits application under the Social Security Act. The respondent, Cleveland Walton had applied for social security disability insurance benefits but was denied by ALJ who found him not disabled within the meaning of the act without assessing his mental capability first. The court ruled in favor of Barnhart stating that it is not mandatory for an ALJ to assess a claimant's mental capacity unless there are indications suggesting potential intellectual impairment or incompetence in understanding and responding appropriately during proceedings. In this case, no such signs were evident as Mr.Walton represented himself competently throughout all stages including filing appeals against initial denial.

In the dissenting opinion for Barnhart v. Walton, Justice Souter disagreed with the majority's interpretation of Social Security Act regulations regarding disability benefits eligibility. He argued that a claimant should not be denied benefits simply because they can perform some work during their period of alleged disability. Instead, he believed that if a person could only engage in sporadic or transitory work due to their impairment, this should not disqualify them from receiving benefits. According to him, such an interpretation would better align with Congress' intent when it established the social security program - to provide assistance for those who are unable "to engage in any substantial gainful activity." The justice also expressed concern about potential unfairness and inconsistency in application resulting from the majority’s ruling.