불문법 refers to "unwritten law" in South Korea, which encompasses legal principles and norms that are not codified in formal statutes. It includes customs, traditions, and judicial precedents that influence legal decisions and societal behavior. This concept plays a significant role in the South Korean legal system, as it helps fill gaps where written laws may be ambiguous or lacking. 법원 (courts) often rely on 불문법 to interpret laws and ensure justice, reflecting the values and practices of the community.