If there was a FISA on PapaD couldn't the white hats have captured info on the black hats….the black hats in UK intelligence and Italian Intelligence.
So MIsfud and Halper thought they were spying on PapaD, but in reality, they were being spied upon and monitored by the white hats because they came in contact with Papa D.
Fisa goes both ways.
If there was a FISA on Carter Page, the white hats captured intelligence on all the black hats pretending to be white hats that contacted Carter Page.