Unanimity rules stop expropriation but also block all non-Pareto legislation.

Evidence

In this case the most extreme form of non insulation would be a referendum that requires a majority of 100 per cent to pass legislation, so that any individual voter can block policy. This institutional arrangement would set expropriation to zero, but would make it impossible to pass any legislation which is not a Pareto improvement. Given that referendum is rarely used, in the majority of institutional settings blocking takes place indirectly, within the institutional structure of delegation. — Philippe Aghion, Alberto Alesina, and Francesco Trebbi, Endogenous Political Institutions, 48

Categorization

• DEFINE: Clarifies ‘non-insulation’ and ‘expropriation’ by pushing the model to its extreme: full blocking power as 100 percent referendum threshold.
• XREF: Connects to public-choice and constitutional-economics literatures on unanimity rules (Buchanan and Tullock) and to veto-player theory.
• SEED: Angle: what every veto point costs — an essay on the trade-off between blocking and governability across constitutions.