"Five people in Japan are poised to launch an unprecedented lawsuit against the government, claiming that a civil law forcing them to choose a single surname after marriage violates their constitutional rights...
...The plaintiffs argue that the civil code's requirement that a single surname be chosen contradicts articles of the constitution guaranteeing individual liberty and equal rights to husband and wife. The five are also seeking 1 million Yen each in compensation from the government."
http://www.guardian.co.uk/world/2011/jan/11/japan-marital-surname-law-challenge