Electoral rules shape how many constraints bind governing parties.

Evidence

Proportional rules tend to produce political systems in which “governing by coalition” is the norm, rather than the exception. In majoritarian systems, the majority party can govern with fewer constraints. — Philippe Aghion, Alberto Alesina, and Francesco Trebbi, Endogenous Political Institutions, 56

Categorization

• XREF: Echoes comparative-politics work on veto players (Tsebelis) and Lijphart’s consensual vs. majoritarian typology.