Ideological Polarization on Constitutional Courts: Evidence from Spain

While constitutional courts in parliamentary democracies are often viewed as resistant to polarization, this study challenges that assumption by analyzing patterns of dissent, party affiliation, and ideological preferences on the Spanish Constitutional Tribunal from 1980 to 2023. Our findings reveal growing ideological polarization, with Spanish constitutional judges increasingly sorting themselves into progressive and conservative camps. Dissents have become both more frequent and more ideologically predictable. They also express more extreme latent preferences. These results indicate that, similar to the U.S. judiciary, constitutional courts in parliamentary democracies are not immune to polarization dynamics.