The capital and the official language of Japan are not determined by law and are not stated in the constitution.
ご質問ありがとうございます。
"The capital and the official language of Japan are"＝「首都と日本の公用語は」
"not determined by law"=「法律で決まっていない」
"and are not stated in the constitution."＝「そして憲法に書かれていない。」
このフレーズを"neither"から始めることもできます↓
"Neither are the capital and the official language of Japan determined by law nor are they stated in the constitution."
ご参考に。
アメリカ合衆国 
