



View photos FBI Director James Comey waits before testifying at a House Intelligence Committee hearing into alleged Russian meddling in the 2016 U.S. election, on Capitol Hill in Washington, U.S., March 20, 2017. REUTERS/Joshua Roberts More

The FBI reportedly used the explosive, unverified dossier detailing President Donald Trump's alleged ties to Russia to bolster its case for a warrant that would allow it to surveil Carter Page, an early foreign-policy adviser to Trump's campaign.

It's a key signal that the FBI had enough confidence in the validity of the document to work to corroborate it and present it in court.

The FBI has been using the dossier as a "roadmap" for its investigation into Russia's interference in the 2016 presidential election since last year, the BBC's Paul Wood reported last month. The document itself was not central to the bureau's argument before a Foreign Intelligence Surveillance Court judge that Page could have been acting as an agent of Russia, according to CNN.

But the raw intelligence contained in the 35-page collection of memos — written by the former British intelligence operative Christopher Steele, who spent 20 years spying for MI6 in Moscow — apparently helped the FBI convince the court that Page could be acting as an agent of a foreign power.

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Some experts have accused the FBI of having political motivations for entering the document into evidence. Others are skeptical that the bureau would have needed to use the dossier at all to bolster its case against Page, an energy consultant turned foreign-policy adviser. Page was already on the FBI's radar because of his ties to a Russian spy who had posed as a UN attaché in New York City in 2013.

A former senior intelligence officer, who requested anonymity to discuss the Foreign Intelligence Surveillance Act process candidly, told Business Insider on Wednesday that using this kind of raw intelligence to build a case for a FISA order was "not uncommon."

"Bear in mind that what one must do in the FISC is to persuade a judge that there is probable cause to believe that someone is the agent of a foreign power," the officer said.

That probable cause is laid out in a "declaration," he added, which is the "new federal term for an affidavit." The declaration is then "generally signed by the agency head" — in this case, FBI Director James Comey — "and cites the evidence that has been obtained" by the relevant agency.

View photos Carter Page More

According to officials who spoke to The Washington Post, the FBI's declaration to the FISC "laid out investigators' basis for believing that Page was an agent of the Russian government and knowingly engaged in clandestine intelligence activities on behalf of Moscow."

The dossier, parts of which have been corroborated by the US intelligence community, alleges that Page was a liaison between the Trump campaign and Russian officials during the campaign. It also alleges that while in Moscow in July, Page and his associates were offered the brokerage of a 19% stake in Russia's state oil company in exchange for the lifting of US sanctions on Russia.

While the evidence put forward in declarations is "usually obtained from an intercept, it need not be," according to the former intelligence officer. "The evidence need not be of the quality that would be admitted into a trial."

The bar for obtaining a FISA order is fairly low. But evidence cited in declarations must still be corroborated through an agency's investigations before it is submitted to the court, officials familiar with the matter told CNN.