The empirical curve answers 'how much' but not 'on what'. The article proposes a two-condition rule: government should brake an activity only when (1) it imposes a net wealth loss on external parties — those who bear cost without being participants in the transaction — summed across all capital kinds (produced, human, natural, knowledge, institutional), and (2) the brake is cost-effective (deadweight loss + enforcement cost + capture risk ≤ |ΔW_ext|). Activities satisfying both conditions are genuine negative externalities: pollution, resource depletion beyond regeneration rates, systemic financial risk.