More than 20 governments have switched off internet access for their citizens in the past year.
Terrorism, public dissidence, censorship, security or protecting business ... their reasons on each occasion vary, but the capability clearly exists.
So, could it happen here? Could Bill English turn up to work one day and flick a magic switch?
The only person to ask a question like that is technology expert Paul Brislen.
He spoke to Duncan Garner.
Watch the video for the full interview.
