If you want to contemplate how FISA may not work just use the example of the 20 terrorists who escaped from a Yemeni prison recently:

An American wanted for allegedly training with the “Lackawanna Six” at an al-Qaida camp was among the 23 men who tunneled out of a Yemeni prison last week, the FBI confirmed Friday.

Authorities earlier said they believed Jaber Elbaneh, 39, was probably among the escapees, but were not certain because of conflicting information, including a posting by the international police organization Interpol that pictured Elbaneh but described someone else.

Elbaneh is charged in Buffalo with providing material support to al-Qaida by attending the al-Farooq training camp run by Osama bin Laden in Afghanistan months before the Sept. 11 terrorist attacks.

Realize that in the pre 9-11 world if this person contacted someone in the US and the NSA detected that contact the entire incident might go unreported. The protection of these barbarians civil rights is more important to some who would argue.