This paper proposes a bicameral reform model for global security governance within the United Nations system, aimed at reducing the risk of large-scale interstate war under contemporary conditions of technological acceleration, asymmetric power shifts, and institutional paralysis. The model is designed to strengthen population-level legitimacy while preserving state sovereignty and legal continuity, enhancing protection for small and microstates, and constraining unilateral escalation authority. Grounded in principles of international law, constitutional governance, institutional practice, and strategic conflict theory, the proposal replaces veto-based paralysis with dual-legitimacy decision-making and liability-bearing objection. It further embeds anti-capture, human rights, and exit safeguards to prevent the concentration of unchecked global power. The reform is presented as a lawful, evolutionary pathway compatible with the United Nations Charter, treaty-based accession, and established international legal norms. It is oriented toward harm-minimization and systemic survivability rather than dominance or centralized global governance.