Whether a Certificate of Appealability must issue when a circuit judge votes to grant one

QUESTION PRESENTED A state prisoner whose federal habeas petition is denied by a district court can appeal only if he obtains a Certificate of Appealability (COA), which requires “a substantial showing of the denial of a constitutional right.” 28 U.S.C. § 2253(c)(2). “At the COA stage,” this Court has long and repeatedly held that “the only question is whether the applicant has shown that ‘jurists of reason could disagree with the district court’s resolution of his constitutional claims or that jurists could conclude the issues presented are adequate to deserve encouragement to proceed further.” Buck v. Davis, 580 U.S. 100, 115 (2018) (quoting Miller—El v. Cockrell, 537 U.S. 322, 327 (2008)). Despite this Court’s clear requirement that a COA issue when any reasonable jurist could disagree with the district court or conclude that the issues warrant further review, the circuit courts are deeply divided on whether, under that standard, a COA must issue if a circuit judge votes to grant one. The Third, Fourth, and Seventh Circuits, by rule, have established that a COA must be granted when any circuit judge votes that the claims deserve appellate evaluation. But the Sixth Circuit panel here denied petitioner a COA over the dissent of a colleague, following the standard established in published authority from the Fifth, Eighth, and Eleventh Circuits. The question presented is: Since a Certificate of Appealability must be granted when reasonable jurists could disagree on the resolution of a constitutional claim or conclude the issues presented are adequate to deserve encouragement to proceed further, must a COA issue when a circuit judge votes to grant one?