In a legal fight over the infamous Trump Dossier — a report prepared by former British spy Christopher Steele that detailed everything from President Donald Trump's supposed romps with prostitutes to coordination with the Russians over the hacking of Democrats — a Russian entrepreneur is arguing the First Amendment doesn't protect the disclosure of sources behind Steele's report.

The legal fight was triggered by BuzzFeed's decision in January to publish the full Trump Dossier. As a result, BuzzFeed has been hauled into court to face a defamation lawsuit from Russian tech entrepreneur Aleksej Gurbarev over claims in the Trump Dossier that his firm used "botnets and porn traffic" to conduct cyber operations against Democratic Party leadership.

In the midst of this defamation case, Gurbarev is attempting to subpoena Fusion GPS, which in 2016 conducted opposition research on Trump and hired Steele to investigate the then-candidate's ties to Russia. The Russian demands documents related to Fusion's clients in connection with the Dossier, the sources of information for the Dossier, efforts to verify allegations in the Dossier, payments made, and more.

Fusion has cooperated with lawmakers and the FBI in their own investigations of whether the Trump campaign coordinated with the Russians, but is fighting Gurbarev's subpoena. Earlier this month, Fusion brought a motion to quash the subpoena in D.C. District Court.

In a memorandum, Fusion argues the Gurbarev lawsuit turns on whether BuzzFeed published the Trump Dossier negligently or with actual malice and whether any reporting privileges are attached to BuzzFeed's publication.

"How the Trump Dossier was created, including Fusion’s engagement and involvement, is of no relevance whatsoever," states Fusion.

Fusion is also asserting a First Amendment privilege.

The firm says "the compelled disclosure of this information would undermine, deter, and chill Fusion's and its clients' rights to engage in political activity and political speech, to speak anonymously, to associate freely with others, and to petition the government. Fusion's ability to associate with its clients, its colleagues, its contractors or subcontractors, and its employees and staff would all be chilled substantially by compelled compliance with the subpoena."

It's added that the identity of the sources are "intensely confidential" and that disclosure "could put those individuals in grave and life-threatening danger."

These are similar to arguments that news organizations often make when looking to protect confidential whistleblowers from compelled disclosure in court. Given that the Supreme Court has held that corporations and unions have free speech rights in Citizens United, does that mean that such entities also enjoy source shielding in certain instances as well?

Here, Gurbarev's lawyers tell a D.C. judge that Fusion's invocation of the First Amendment is "astonishing."

"Fusion would have this Court believe that its work conducting paid opposition research has somehow transformed it into a political organization and that the identity of its clients, colleagues, contractors, subcontractors, employees, and staff are the equivalent of a 'membership list,' the disclosure of which would somehow implicate those individuals' First Amendment rights," states a Gurbarev opposition brief filed on Tuesday. (Read here.)

Gurbarev's lawyers go further.

"[I]t is worth pausing for a moment to also consider precisely how wide a swath of protection Fusion believes it would be entitled to if a privilege were to apply," they continue. "According to Fusion, there is no aspect of its work at all that is not protected: it can hide not only the identity of its clients, but also every fact concerning its collection of information about [Gurbarev] reported in the December Memo, what it did (or did not) do to verify the information, which media outlets it provided the December Memo to, and what it told recipients of the December Memo. In other words, Fusion is saying that it is entitled to call a press conference; disseminate defamatory information about [Gurbarev] to the gathered reporters (and others) and then refuse to even reveal what it said and to whom, because ... First Amendment. This position is absurd on its face."

As far as relevancy, Gurbarev's attorneys say that to prevail in the defamation lawsuit, he must do more than demonstrate actual malice on BuzzFeed's part.

"First, as Plaintiffs in a defamation action, the burden is on [Gurbarev and his companies] to establish that the statements complained of were false," states the opposition brief. "Knowing the identity of the source of such information may well be key to proving its falsity."

Gurbarev wants to know if the sources behind the Trump Dossier were his competitors, a neighbor with a personal grudge, a stranger with an agenda, or a figment of Steele's imagination. He also wishes to know if Fusion or Steele had ever utilized those sources previously or if there's exculpatory information.

If Gurbarev's lawsuit does make it to trial, there's the prospect of the Trump Dossier being tested for its truth or falsity.

As the bid to enforce the subpoena puts it, "Although it is certainly true that Plaintiffs know that the statements made about them in the December Memo are false, it is equally true that they are entitled to marshall all of the evidence to persuade a jury of the same."