Shigejiro Tabata, an authority on international public law, died Thursday of a heart attack at a Kyoto hospital, his family said. He was 89.
Tabata, a native of Maizuru, Kyoto Prefecture, described the dropping of atomic bombs on Hiroshima and Nagasaki by the United States in 1945 as a violation of international law.
He was the last survivor of a group named The Seven-Member Committee Calling For International Peace, which also included the late Nobel laureate Hideki Yukawa.
As an international law expert, Tabata researched issues such as the Japan-U.S. security system and Japan's self-defense rights.
Tabata criticized movements pressing for revisions to the war-renouncing Constitution by emphasizing the significance of everlasting peace.