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.