Amending or revising an existing constitution. Such changes usually require special procedures like parliamentary approval and often a national referendum.
憲法改正の是非をめぐって激しい議論が続いている。
Intense debate continues over whether to amend the constitution.
憲法改正には国民投票が必要だと法律で定められている。
The law stipulates that a national referendum is required for constitutional amendment.
彼らは憲法改正を求める署名運動を始めた。
They started a petition campaign calling for a constitutional amendment.