6) the warrant(s) is(are) legally valid, but is(are) based on invalid data, and/or invalid analysis based on that data
To me, it would make the most sense if most of the stuff being argued about was slipped over the heads of the legal folks (including fisa judges) and political staffers via an “expert” analysis presented to the fisa judges.
it only takes one technical “expert” to testify, with no alternative analysis required to be presented by the non-adversarial proceeding, for the entire process to be corrupted. if my understanding of the fisa proceeding is more or less correct(?), this could be the achilles’ heel of the entire process.
obama and his lieutenants would naturally gravitate to an achilles’ heel of any such proceeding in order to subvert it, i.e., in order to get the ends to justify the means.
it all depends on the definition of the word “valid”...
The whole “narrative” was probably dishonest and flawed from the start. One article (sorry don’t remember where at the moment) said that CIA’s Brennan started the whole thing back in spring 2016 when he received a report from the Baltics that Russian money was going to the Trump campaign.
Think of how ridiculous this idea is, multi-billionaire Trump had not the slightest NEED for any Russian money AND (of course) such a thing would be the kiss of death if ever revealed.
So on the basis of a totally implausible and probably concocted tale (think of the “Golden Showers” b.s. in the notorious “dossier”), CIA’s Brennan gets a 6-agency intel task force assembled, leads to the FISA warrant requests and more, etc.
This is not to say there may not have been some kind of Russian person(s) who wanted to get connected to the Trump campaign, etc. All sorts of foreign entities are trying to make good contacts in US circles of power all the time. BUT, the idea that Team Trump would knowingly accept any money or support for the campaign from Russian sources has always been ridiculous in the extreme.
Now the Clintonistas, on the other hand..... Russia, China, all sorts of shady money and characters flow in.