FILE - This Nov. 10, 2017, file photo shows Russia's President Vladimir Putin, left, and Russian metals magnate Oleg Deripaska, right, walking to attend the APEC Business Advisory Council dialogue in Danang, Vietnam. (Mikhail Klimentyev, Sputnik, Kremlin Pool Photo via AP, File)

Russian billionaire Oleg Deripaska sued the Treasury Department and Secretary Steven Mnuchin in U.S. federal court to demand the lifting of remaining U.S. sanctions against him, alleging the measures were illegal and harmed his finances and reputation.

Deripaska, an ally of Russian President Vladimir Putin, claimed that Washington’s 2018 sanctions were “completely untethered” from “legal criteria.”

The lawsuit, filed in district court in Washington, D.C., said the oligarch’s net worth has fallen by more than $7.5 billion, or 81 percent, since he and some of his companies were sanctioned for what Treasury called his support of “the Kremlin’s global malign activities.”

In January, the Treasury Department lifted sanctions on three Deripaska-connected companies, but left in place the sanctions on Deripaska himself.

“Treasury does not generally comment on pending litigation,” an agency spokesman said Friday.

Sanctions experts said it is not unusual for sanctioned individuals to sue Treasury. The government usually wins the cases, “since the judiciary is pretty deferential to [Treasury] and the government on issues of national security,” said Peter Harrell, a former State Department official who worked on sanctions policy during the Obama administration.

The D.C.-based lawyer representing Deripaska in the case, Erich Ferrari of Ferrari & Associates, didn’t immediately respond to requests for comment. Ferrari’s online profile says he has previously “worked to have names removed” from Treasury sanctions lists.