A New York state court is expected to rule Friday on Russian-Canadian billionaire Alex Shnaider's attempt to obtain a client file from Boies Schiller Flexner, which previously represented Shnaider in contract litigation and has asserted a retaining lien over the file because its former client owes the firm legal fees.

Shnaider, now represented by Michael Bowen of Kasowitz Benson Torres, filed a petition on Wednesday, asking a Manhattan state court judge to issue an immediate injunction that would require Boies Schiller to provide a copy of Shnaider's file in a separate lawsuit that has a trial scheduled to begin in December. New York Supreme Court Justice Debra James is expected to hold a hearing on the petition Friday morning.

Kasowitz also represents Shnaider in the underlying contract case, in which the billionaire was accused in Manhattan federal court of breaching agreements with former business partner Eduard Slinin, according to court records in that suit.

Shnaider and Slinin, who bonded over their shared roots as Jewish emigrants from the former Soviet Union, teamed up, starting in the mid-2000s, on a plan to buy several private jets from Bombardier Inc. The idea was to use Shnaider's business connections to buy Learjets and other planes, and then “flip” them for a profit by selling the aircraft to Slinin's contacts, many of whom were Russian or Ukrainian businesspeople, according to court records. The business partnership later soured, however, and Slinin sued in 2015.

(Separate from the jet case, Shnaider's reported links to Russia have landed him in the news recently, specifically related to his past business partnership with President Donald Trump, whose company licensed the Trump brand for use on a skyscraper that Shnaider developed in Toronto.)

In early September, U.S. District Judge Richard Sullivan, who is overseeing the jet case, granted the firm's motion to withdraw from representing Shnaider. The ruling came just days after Boies Schiller's Karen Dyer sent a letter asking to withdraw as defense counsel “due to irreconcilable differences with Mr. Shnaider regarding the payment of BSF's legal fees.”

Before that, Boies Schiller served as Shnaider's defense counsel in the jet case from February 2016 until the representation ended in early September. During their time representing him, the firm helped Shnaider narrow the case, convincing Sullivan to dismiss claims for breach of fiduciary duty and unjust enrichment. That left Slinin with a single claim for an accounting on dissolution of his partnership with Shnaider.

In the state court petition, Shnaider alleges that Boies Schiller asserted a retaining lien on his case file in the jet case because of the dispute over unpaid legal fees. Regardless of who's right in the legal fee dispute, Shnaider argued, Boies Schiller should still have to provide at least the portion of the client file that contains discovery related to the jet case, in light of the upcoming trial.

“Irrespective of the merits of any claim BSF may have to unpaid legal fees, withholding discovery on the eve of trial will grievously harm BSF's own former client,” Shnaider's lawyers at Kasowitz wrote in the state court petition.

As of Thursday afternoon, Boies Schiller hadn't submitted any state court filings in response to Shnaider's petition, and representatives for the firm declined to comment.