Modern networked systems—digital platforms, financial infrastructure, government services—routinely claim voluntary participation based on the existence of exit options. This paper demonstrates that legal exit does not equal viable exit. We introduce the Exit Coercion Index (ECI): a formal measure of functional economic penalty incurred by leaving a system, even when exit is legally permitted. ECI captures coercion-by-dependency: a form of structural coercion invisible to traditional consent analysis, where participation is technically voluntary but practically mandatory. When exit destroys income, severs access to essential infrastructure, eliminates network value, or requires years to recover, consent is manufactured regardless of legal permission. We integrate ECI into Zero Leap Theory by refining the Consent gate: 𝒞_eff = 𝒞_legal · 𝒞_viable, where 𝒞_viable = (1+ECI)⁻¹. As ECI approaches infinity, effective consent approaches zero. This formalization enables auditable assessment of consent claims in networked systems. The paper provides:(1) Formal ECI definition with two formulations (weighted and maximum-rule)(2) Measurable proxies: income loss (ΔY), infrastructure access (ΔA), network value (ΔN), recovery time (T_rec)(3) Operational thresholds: ECI ≤ 0.25 (GO), 0.25-0.50 (CONDITIONAL), > 0.50 (BLOCK), ≥ 0.75 (LOCK-IN TRAP)(4) IAS-ECI Protocol: 12-item audit checklist(5) Anti-proxy-washing rule: audits claiming consent based solely on legal exit availability are invalid by construction(6) Juridical standard: Coercion-by-Dependency Negligence Case studies validate ECI across domains: Meta/Facebook (ECI 0.52-0.80), modern banking systems (ECI 0.85-0.90), China Social Credit (ECI ≈ 1.0), and platform economy/Uber (ECI 0.62-0.90). Core principle: If leaving destroys your economic life, your "consent" is coercion wearing a mask. Exit allowed ≠ exit feasible. A cage with an unlocked door is still a cage if walking out means death.