How does the voluntary repo law work?

I guess as soon as they write one we will find out.

There is no real law, you can go and talk to the loan holder and see if they will take it back but they don't have to,

After that it works like any repo, they sell the item and you will owe the balance often as much as you do now after they add all the fees.

But basically you just stop paying and they will repo at some point