O que significa a expressão lay down the law?

I have a 4-year-old nephew and everybody knows that's the phase they tend to misbehave the most. They're exploring the world around them and most of all exploring people's reaction around them.

My brother is a first-time dad and what usually happens to first-time parents is that they are constantly bombarded with advice regarding how they should educate their kids. "Let your child know you", "don't let guilt rule you", "ask for help", so on and so forth. But the one piece of advice that can be reoccurring is the expression we are learning today: "lay down the law".

When you lay down the law in your house to your kids or whoever may be, you're giving them a directive or order, scolding them, dictating how to bebave, making something very clear, often sternly or forcefully. 

Do you think that's good advice? Did you respect your parents when you were a child because they would lay down the law otherwise? Leave your answers down in the comment section. Talk later!!!!