[T]he allegation made by various news sources is that, in connection with a multi-agency intelligence investigation of Russian interference with the presidential election, the FBI sought an order from the Foreign Intelligence Surveillance Court authorizing them to monitor transactions between two Russian banks and four persons connected with the Trump campaign.  The Guardian's report alleges that initial applications submitted over the summer, naming "four members of the Trump team suspected of irregular contacts with Russian officials," were rejected by the FISC. But according to the BBC, a narrower order naming only the Russian banks as direct targets was ultimately approved by the FISC in October.  While the BBC report suggests that the surveillance was meant to ferret out "transfers of money," the Mensch article asserts that a "warrant was granted to look at the full content of emails and other related documents that may concern US persons."

Taking all these claims with the appropriate sodium chloride seasoning, what can we infer?  First, contrary to what many on social media--and even a few reporters for reputable outlets--have asserted, the issuance of a FISA order does not imply that the FBI established probable cause to believe that any Trump associate was acting as an "agent of a foreign power" or engaged in criminal wrongdoing.  That would be necessary only if the court had authorized direct electronic surveillance of a United States person, which (if we credit the BBC report) the FISC apparently declined to do.  Assuming the initial applications were indeed for full-blown electronic surveillance orders, then the fact that the FBI supposedly did name the Trump associates at first would suggest they may have thought they had such evidence, but one would expect the FISC to apply particularly exacting scrutiny to an application naming persons associated with an ongoing presidential campaign.  An application targeting only foreign corporate entities--especially entities openly controlled or directed by the Russian government--would require no such showing, even if the FBI's ultimate interest were in communications concerning those U.S. persons.

It's worth noting here that, contra Trump's claim on Twitter, none of the articles in question claim that phones were tapped.  Indeed, it's not even entirely clear that the order the FISC finally issued in October was a full-blown electronic surveillance warrant requiring a probable cause showing.  If the FBI was primarily interested in obtaining financial transaction records, corporate documents, and (depending on both the facts and the FISC's interpretation of the FISA statute) perhaps even some stored e-mail communications, that information might well have been obtainable pursuant to a §215 "business records" order, which imposes only the much weaker requirement that the records sought be "relevant to an authorized investigation."  The BBC's use of the word "intercept" to describe the investigators' aim, as well as Mensch's characterization of the order as a "warrant," both suggest full-blown electronic surveillance, but reporters aren't always particularly meticulous about their use of legal terms of art, and similarly, sources with indirect knowledge of an investigation may not be scrupulously exact about the distinction between an "order" and a "warrant."

In either event, there's nothing here to suggest either the direct involvement of President Obama nor any clear indication of a violation of the law.  If, however, the primary purpose of the investigation was to build a criminal case against U.S. persons in the Trump camp, then the use of FISA authorities to gather information by naming foreign entities sounds like "reverse targeting"--tasking collection on a foreign target when your real interest is a U.S. person with whom they're communicating.  That would be, to use the technical term, highly shady even if not unlawful. Thanks to the Patriot Act, however, FISA authorities may be used in investigations that have a "significant" foreign intelligence purpose, even if the "primary" purpose is criminal prosecution--a change from the prior standard imposed by the courts, which had required that foreign intelligence be the "primary" purpose of surveillance under the aegis of FISA, precisely to prevent authorities from evading the stricter requirements imposed by Title III, the statute that covers wiretapping for domestic criminal investigations.