The Justice Department recently changed its policy on notice to criminal defendants about the use of evidence derived from surveillance under Section 702 of FISA. Press reports have treated the change as momentous, with the New York Times and the Associated Press predicting that the new policy will likely lead to a Supreme Court case on whether Section 702 violates the Fourth Amendment. I have a different view. My sense is that the notice is less significant than many believe, and that a future Supreme Court decision on the validity of Section 702 isn't particularly likely in the short term---and maybe even in the long term.
First, the additional notice provided by DOJ is so bare bones that it won't be very helpful. In the United States v. Muhtorov case, the notice filed merely states that some evidence in the case was obtained or derived from acquisition of foreign intelligence information under 702. That's it. Muhtorov's lawyers don't know what information was obtained, or when, or in what circumstances. His lawyers can make some educated guesses about the role of Section 702 in his case. But they don't really know, and his lawyers can't make much of this disclosure unless DOJ responds to a future motion to suppress by disclosing more details. DOJ might disclose more details, but that's going to be another battle Muhtorov's lawyers will have to fight: Muhtorov has the burden to show that his Fourth Amendment rights were violated, but only DOJ knows the facts. So DOJ has every incentive not to say more unless a court requires it to say more.
Granted, a district court might demand that DOJ say more. My understanding is that under 50 U.S.C. § 1881e, a court has to follow the judicial review procedures in 50 U.S.C. § 1806(f) when a notified defendant files a motion to suppress. Section 1806(f) contemplates an in camera and ex parte assessment of lawfulness, and I gather that a district court judge might require DOJ to disclose what happened (even if only to the court, at least initially) to help the judge make that call.
But even so, that doesn't mean that a facial challenge to Section 702 could be made. In Fourth Amendment law, challengers normally have to challenge the lawfulness of the surveillance against them, not the constitutionality of the statute that allowed monitoring. See Sibron v. New York, 392 U.S. 40, 59-62 (1968). The basic idea is that the Fourth Amendment isn't violated until a search or seizure actually occurs. It's executive branch action, not the approval of the legislative branch, that matters. So it makes no sense to ask whether a statute violates the Fourth Amendment; what matters is whether executive action in reliance on the statute violated a particular person's Fourth Amendment rights. Under that standard, Muhtorov could argue that monitoring his e-mails and/or telephone calls violated his Fourth Amendment rights, but he couldn't bring a facial challenge to Section 702 as a whole.
Perhaps a judicial decision ruling on whether Muhtorov's own rights were violated could nonetheless get to the key questions underlying the constitutionality of Section 702. But even then, courts probably have an easy way to avoid ruling on the merits. Under Illinois v. Krull, 480 U.S. 340 (1987), the exclusionary rule does not apply when the government violates the Fourth Amendment in good-faith reliance on a statute allowing a search or seizure. Under Krull, the exclusionary rule shouldn't apply if the government followed Section 702 even if the surveillance Muhtorov's Fourth Amendment rights. A court applying Krull could deny the motion to suppress on those grounds without even reaching the merits. See, e.g., United States v. Ferguson, 508 F.Supp.2d 7 (D.D.C. 2007). (To be fair, it's not entirely certain if Krull would apply given the statutory suppression standard of 50 U.S.C. § 1806(g); the language is unclear about whether it maintains the good-faith exception. But I suspect it does, at least in the context of a Fourth Amendment challenge instead of a statutory challenge.)
Even if courts somehow overcome all of these hurdles, and we end up with a federal appellate ruling in Muhtorov on the facial validity of Section 702, I doubt the Supreme Court would intervene unless DOJ wanted the Justices to take the case. It's true that the Justices reviewed the Second Circuit's decision in Ammesty International v. Clapper, and so they have expressed interest in Section 702 before. But Clapper created a clear circuit split on the standing issue: The Second Circuit's Clapper decision was written as if to invite the Supreme Court to review it. A lower court decision on the Fourth Amendment question would be quite different. No court has ever directly addressed the Fourth Amendment issues that Section 702 raises, and I doubt the Justices would intervene absent a circuit split or a federal appellate ruling striking down the statute.
Taking all of these arguments together, I'm skeptical that the Supreme Court is likely to rule on the validity of Section 702 any time soon.