Judges. Officers. That is what we are told to place at our gates to maintain law and order. (Or order and law).
Chazal teach us that every person requires these safeguard measures at all times. Perhaps our greatest weapon that causes the most harm is our power of speech. Hashem created us with all sorts of protective gear to keep us from speaking the wrong words (teeth, closed mouth) and from hearing evil about others (ear lobes). All we have to do is use them correctly.