During the Edo period, the government had each neighbourhood form groups of five and they were meant to watch one another to make sure they didn't break the law.
この場合、次のような言い方ができますよ。
ーDuring the Edo period, the government had each neighbourhood form groups of five and they were meant to watch one another to make sure they didn't break the law.
「江戸時代、政府は近隣で５人組を作らせ、互いに監視し法律違反をしないようにさせた」
to form groups of five「５人組を作る」
to watch one another「お互いに監視する・見張る」
to break the law「法を犯す・法律を違反する」
ご参考まで！
カナダ 
