Article content continued

Kasowitz, whose scrappy style in the courtroom mirrors Trump’s approach to politics, represented Trump in various matters for more than a decade before he took on either Deripaska’s company or Sberbank, according to one of Kasowitz’s partners in the firm.

Trump has turned to Kasowitz for matters that include debt restructuring and suing an author who Trump said undercounted his net worth. On Thursday, Kasowitz became the public face of Trump’s counterattack on former FBI director James Comey, challenging the former federal prosecutor’s credibility and calling for Comey to be investigated for leaks after his testimony to Congress.

We apologize, but this video has failed to load.

tap here to see other videos from our team. Try refreshing your browser, or

As Kasowitz takes on his most high-stakes work for Trump yet, the lawyer’s Russian clients could cause complications.

“If the behavior of a Russian client of the firm or its relationship with Trump becomes an issue in the investigation, a conflict could arise,” said Stephen Gillers of New York University Law School, an expert on legal ethics.

Deripaska has said congressional investigators have contacted his attorneys seeking information about his business dealings with Paul Manafort, a Trump campaign manager during the presidential campaign. More than a decade ago, Deripaska invested in a fund that Manafort set up in the Cayman Islands that bought assets primarily in Ukraine.

The Associated Press reported in March that Manafort “secretly worked for” Deripaska as far back as 2006 to influence politics and business dealings inside the United States to benefit Putin’s government. Manafort signed a $10 million annual contract beginning in 2006 and maintained a business relationship until at least 2009, the AP reported.