Complex sentence: An officer from the Ministry of Justice who was invited to comment has stated that the action by Shibuya ward is legal because the certificate issued is not marriage certificate and the current Japanese legal code does not prohibit "partnership" of the same sex couple.
Split into simpler sentences: An officer from the Ministry of Justice who was invited to comment the action by Shibuya ward. He has stated that the action by Shibuya ward is legal because the certificate issued by Shibuya ward is not marriage certificate and the current Japanese legal code does not prohibit "partnership" of the same sex couple.