The New York Times is still hammering away at the Knoedler case, today it is a story that points out there is no legal recourse to remove fake works from the market:

The resale of fakes is a persistent and growing problem without a good solution, say collectors, dealers, artist estates and law enforcement agencies. Although the Federal Bureau of Investigation can seize forgeries in criminal cases, these represent only a tiny portion of the counterfeit art that is circulating.

“They churn through the market,” James Wynne, an F.B.I. special agent who handles art forgery cases, said of fakes.

There are no clear rules for what happens to phony art after it is identified. “It all depends what the facts are, what the art is, how many works are involved and how expensive they are,” he said. […]

Jack Cowart, executive director of the Lichtenstein Foundation, said that during the years that it authenticated works by Roy Lichtenstein, he regularly noticed that collectors informed that they had a fake would later quietly sell it as genuine. “And then we’d find somebody else would send the same work to us six months later” asking for it to be authenticated, he said.

Fake Art May Keep Popping Up for Sale (New York Times)