This Latin phrase relates to an old Greek principle of justice which translates literally into English as “to each his own”. In Plato’s Republic, Socrates offers the provisional definition that “justice is when everyone minds his own business, and refrains from meddling in others’ affairs”. Everyone should do according to his abilities and capabilities, to serve the country and the society as a whole. Also, everyone should receive “his own” (e.g., rights) and not be deprived of “his own” (e.g., property).
Suum cuique was used as a motto by the Order of the Black Eagle (Hoher Orden vom Schwarzen Adler) which was the highest Knightly order of the Kingdom of Prussia. The motto continues to be used today in Germany in the insignia of the Feldjäger (or Military Police) and the Berlin based Masonic Lodge, also known as the Black Eagle Lodge.