A consumer can't initiate a MoneyPak chargeback, but a report of fraud can cause Green Dot to ask for the receipt proving you bought the MoneyPak yourself. There's a piece of malware going around (FBI MoneyPak virus) where your system is held hostage until you pay off the ransom with a MoneyPak.
I can imagine the authorities working with Green Dot where they have some MoneyPak codes that will be accepted but because they were obtained through fraudulent means would later be reversed. Here's more on the scam:
- http://www.gamersdailynews.com/story-29007-How-FBI-Moneypak-Scam-Victimized-Me.html