I'm not sure I understand the point about Article III courts not being able to be abolished. Several courts established by the judiciary act of 1801 were abolished early in Jefferson's term.
I agree that it doesn't explicitly say that the FISA court is an article III court but some of the holdings are hard to understand if the court isn't. For instance, the court rejected the argument that it was not "properly constituted under article III because the statute does not provide for life tenure on the FISA court." If the court held it wasn't an article III court it would have not considered the argument!
Additionally, from a quoted decision in that section(Megahey, 553): "As such, with respect to their assignment to FISC for a seven-year term with no additional compensation, FISC judges do not differ from other federal judges who sit from time to time and when the need arises on courts other than that to which they are appointed by temporary designation"
I'm not sure there is any indication that the judges are serving on a non-article III court here. They certainly would 'differ' substantially from the example presented if they did.
Well, the FISA court is really strange in any case. For starters, I'm not sure how FISA warrants are actually warrants in any sense at all. I'm sure congress could screw it up even more.
Thanks!