Local judges tend to be elected from the district they are in and while they’re not part of a political party per se they run on a platform of being tough on crime or light on drug infractions or that kind of thing. Seeing how the political parties in America are so polarized ideologically that essentially leads to conservative judges being elected in conservative districts.

For higher state courts and federal courts a judge is nominated by the executive branch, and then confirmed or denied by the legislative branch. What started as an attempt at balance between the arms of government has just lead to more tribalism to further agendas.