Judges are theoretically elected by their respective local people's assemblies, but in practice they are appointed by the Workers' Party of Korea. The penal code is based on the principle of ''nullum crimen sine lege'' (no crime without a law), but remains a tool for political control despite several amendments reducing ideological influence. Courts carry out legal procedures related to not only criminal and civil matters, but also political cases as well. Political prisoners are sent to labor camps, while criminal offenders are incarcerated in a separate system.