Even if sovereign immunities fail to prevent holdout litigation before a domestic court, bondholder claims may still be effectively forestalled by the operation of collective action clauses. The limits of first-generation CACs have been partially overcome, and their use in sovereign bonds is now common in the United States and is mandatory in the Eurozone. This strengthened protection for debtor sovereigns is accompanied by the introduction of accountability mechanisms that guarantee fairness in the implementation of debt workout processes. This study has concluded that the development of CACs embodies a possible balance between bondholder protection and respect for debt restructuring by sovereigns. Although a more delicate question arises when a defaulting sovereign introduces a CAC mechanism by modifying the relevant domestic law governing sovereign debt instruments, such a measure may fall within the margin of discretion exercised by the debtor sovereign as the governance organ primarily responsible for addressing its sovereign default, provided that its accountability is duly discharged in and out of courts or tribunals.