In two consolidated appeals, James Brown challenged the denial of his federal post-conviction motion by a magistrate judge acting with the parties’ consent to final jurisdiction. The Eleventh Circuit construed § 636(c)’s grant of consent-based authority in civil matters not to cover a § 2255 collateral challenge to a federal conviction or sentence. It therefore held that the magistrate judge lacked statutory authority to enter final judgment. The panel avoided deciding whether the procedure also violated Article III and expressed no view on the substance of Brown’s § 2255 claims. It vacated the denial and returned the motion to the district court for disposition.