They didn't need the law until Lucifer established
the foothold of the knowledge of good and evil.
Having sex with Eve started it.

Lucifer is the tree of knowledge of good and evil.
Eve partook of Lucifer's seduction.
It opened her eyes, she knew of good and evil.
God didn't want them to know.

It started the whole thing over again
of Lucifer trying to take God's Throne
in the "second earth age".

Lucifer had already convinced a third of
God's children in the "first earth age" to
follow Lucifer. That's why we are in the
"second earth age"...to make a decision.
Either your for God or your not.
Either your on the bus or your off the bus.

God had to come up with His Plan to
fix Lucifer's wagon.
5 Spiritual Laws and 5 Civil Laws,
The 10 Commandments.

But even after that, man still had
free choice to decide whether your
on the bus or off the bus.

And so it goes.