The FBI used that infamous Russian dossier as part of their justification for requesting a FISA court order to monitor former adviser Carter Page.

Source

Courtesy of CNN:

The FBI last year used a dossier of allegations of Russian ties to Donald Trump's campaign as part of the justification to win approval to secretly monitor a Trump associate, according to US officials briefed on the investigation. 

The dossier has also been cited by FBI Director James Comey in some of his briefings to members of Congress in recent weeks, as one of the sources of information the bureau has used to bolster its investigation, according to US officials briefed on the probe. 

This includes approval from the secret court that oversees the Foreign Intelligence Surveillance Act (FISA) to monitor the communications of Carter Page, two of the officials said. Last year, Page was identified by the Trump campaign as an adviser on national security. 

Officials familiar with the process say even if the application to monitor Page included information from the dossier, it would only be after the FBI had corroborated the information through its own investigation. The officials would not say what or how much was corroborated.

Well ti appears that the Russian dossier compiled by former MI-6 agent Christopher Steele was not so uncorroborated after all.

Carter Page of course continues to protest his innocence, but bear this in mind:

To obtain court permission to target Page, the FBI and Justice Department would have to present probable cause that he was acting as an agent of a foreign power, including possibly engaging in clandestine intelligence gathering for a foreign government. Comey and other top Justice Department officials would have to sign off on the application, which government officials say involves a rigorous review process.

Yes they do not simply hand out FISA court orders like candy on Halloween.

Which of course brings us back to that post from Louise Mensch:

Sources with links to the intelligence community say it is believed that Carter Page went to Moscow in early July carrying with him a pre-recorded tape of Donald Trump offering to change American policy if he were to be elected, to make it more favorable to Putin. In exchange, Page was authorized directly by Trump to request the help of the Russian government in hacking the election.

Simply put, the threads are starting to come together in a way that makes the Trump presidency feel a little temporary. 

Don'tcha think?