The Honorable MA Yongjoo was born on July 1, 1969, in Hapcheon, Gyeongsangnam-do. Justice Ma earned his LL.B. from Seoul National University’s College of Law and passed the 33rd National Judicial Examination in 1991 while attending the school. Subsequently, he completed his military service as a judge advocate in February 1997.

Justice Ma has held various judgeship positions throughout the judiciary. He has held the positions of Director of Personnel Management and Inspector General for Judicial Ethics in the Korean Supreme Court's National Court Administration (NCA), an institution responsible for overseeing court administration. He also assumed responsibilities in the Research Division of the Supreme Court as a Research Judge, Deputy Head, and eventually as Head of the Research Division. Most recently, he served as the Presiding Judge of Seoul High Court and was appointed as Justice of the Supreme Court of Korea on April 9, 2025.

During his 27 years as a judge, Justice Ma has presided over various cases, including civil, administrative, and criminal matters. Throughout his distinguished career, Justice Ma has guided his actions by a core motto inspired by the passages from the Book of Great Learning (大學章句 Dae Hak Jang Gu), emphasizing the values of caring for one's family, being loyal to one's country, respecting justice, and serving the people as one would serve their parents. In this framework, the nation represents the Free Democratic Republic of Korea and its constitutional order, heaven symbolizes justice, and people represent the litigants, particularly vulnerable members of society. He is committed to delivering fair rulings while acknowledging the distress that litigation can cause. His six years of experience in various research judge positions, including as the Head of the Research Division at the Supreme Court, have equipped him with a solid background in legal principles. This experience has enabled him to make notable contributions to the research significant cases, contributing to the Court's development of relevant and rational legal doctrines.

Justice Ma has authored numerous papers that serve as valuable resources for his colleagues, fellow judges, and legal practitioners. He has demonstrated his extensive legal theory and practice expertise through contributions to annotated commentaries on Civil Procedure Law and Criminal Law. He played a key role in establishing a system for recognizing amending claims in administrative litigations, which was essential for the court's early operations. Additionally, Justice Ma's writings on amending claims under the Administrative Litigation Act advocated for a distinct approach from that of the Civil Procedure Act. He conducted a comprehensive examination of the legal doctrine surrounding previous case law related to statutory appropriations for distributing auction dividends. Through his publications, he introduced new legal issues and proposed potential solutions.

Justice Ma views judicial power with a strong sense of responsibility rather than entitlement. He is dedicated to managing each trial with care and sincerity, making sure that no case is neglected. By upholding the Constitution and the law, he strives to create a judicial system that truly represents the will of the people.