The article speaks generally about when the FBI can access email. It doesn't have a source which says exactly which approach was used in this case. They may hav

The article speaks generally about when the FBI can access email. It doesn't have a source which says exactly which approach was used in this case. They may have used any of the methods mentioned -- prosecutor subpoena, judge, or even Petraeus' prior or current written authorization -- depending on the exact timing of when its contents were examined.