Scholars have long debated Congress’s power to curb federal jurisdiction and have consistently assumed that the constitutional limits on Congress’s authority (if any) must be judicially enforceable and found in the text and structure of Article III. In this Article, I challenge that fundamental assumption. I argue that the primary constitutional protection for the federal judiciary lies instead in the bicameralism and presentment requirements of Article I. These Article I lawmaking procedures give competing political factions (even political minorities) considerable power to “veto” legislation. Drawing on recent social science and legal scholarship, I argue that political factions are particularly likely to use their structural veto to block jurisdiction-stripping legislation favored by their opponents. Notably, this structural argument is supported by the history of congressional control over federal jurisdiction. When the federal courts have issued controversial opinions that trigger wide public condemnation, supporters of the judiciary–even when they were only a political minority in Congress–repeatedly used their structural veto to block jurisdiction-stripping proposals. This structural approach also provides one answer to a puzzle that has particularly troubled scholars: whether there are any constitutional limits on Congress’s authority to make “exceptions” to the Supreme Court’s appellate jurisdiction. The structural safeguards of Article I have proven especially effective at preventing encroachments on the Supreme Court’s Article III appellate review power.