Trusting the lawmakers, and elected / appointed agents in general, to do the right thing is another interesting problem. It does not seem completely solved yet, too.
"Law and order" might arguably about trusting such agents; but rule of law is more the opposite. It's about putting those agents in a situation where they tend to enforce rules that they cannot easily manipulate.
You are right that is a hard thing to do, and no society has ever done it perfectly. But western democracies do it surprisingly well, and do so using a playbook of principles that has been understood and written about since the 18th century.
