What accounts for activism on high courts? Under traditional democratic theory, courts are supposed to act as an important check on governmental excesses or abuses. Yet, most theory regarding the development of court systems recommends that young courts refrain from challenging the decisions of government. In this paper, I explore the avenues through which constitutional courts assert judicial power within developing democracies. Using a unique database of decisions from the Polish, Latvian, and Slovenian constitutional courts, I find evidence that policy preferences matter to court outcomes. Specifically, I find that judicial panels are much more likely to overturn laws when there is an ideological divergence between the court and the law under review. At the same time, the propensity of courts to overturn laws is also greater when certain actors propose the constitutional challenge: specifically, government monitoring and oversight agencies are particularly successful in challenging acts and laws. These agencies are publicly popular actors, which could contribute to their success. However, I argue the governmental monitoring role these agencies serve also can alleviate concerns that judicial rulings will not be complied with. Both findings have potentially important implications for democratic performance, particularly in developing democracies.
