George Lidnemann Journal by George Lindemann "The Deep Freeze in Art Authentication" @wsj by Jennifer Maloney

George Lidnemann Journal by George Lindemann "The Deep Freeze in Art Authentication" @wsj by Jennifer Maloney

Joe Simon, left, sued the Warhol foundation after it said his 'Self Portrait' wasn't an authentic Warhol. Madeleine Farley

As contemporary-art prices soar, collectors want assurances that works are authentic. But it is becoming increasingly difficult to get an answer.

A series of high-profile authentication disputes have made art historians reluctant to offer opinions, and prompted several artist estates and foundations to disband their authentication boards.

The authentication deep freeze means uncertainty for artworks that haven't previously been authenticated or included in an artist's catalogue raisonné, or scholarly inventory. Such works may end up occupying a murky middle ground and sell for less than authenticated works, experts say. "There are people who are willing to take educated gambles," said Peter Stern, an attorney who specializes in the art world. Others can't be sold at all.

In 2007, Joe Simon, a London-based filmmaker, sued the Andy Warhol Foundation for the Visual Arts after the board ruled inauthentic a silk-screen featured during the artist's lifetime on the cover of his catalogue raisonné. The foundation announced in 2011 it was disbanding its authentication board after it says it spent more than $6 million fighting the suit. Mr. Simon said he dropped it because he couldn't afford to continue.

"Protecting collectors, it's not our job," said Michael Straus, chairman of the Warhol foundation. "I don't think putting the burden of that due diligence on an artist estate, especially in the absence of sufficient legal protections, is appropriate."

In February, a group of collectors sued the Keith Haring Foundation, saying the organization had cost them at least $40 million by publicly declaring their paintings "counterfeit" and declining to consider information that could establish their provenance. The foundation's authentication board was dissolved in 2012.

Collectors sued the Keith Haring Foundation after it declared some works, including this one, counterfeit. Connie Grisley Images

The case with the greatest chilling effect for scholars was one that led to the closure of Manhattan's Knoedler & Co. gallery. Last year, Long Island art dealer Glafira Rosales pleaded guilty to conspiring to pass off a Queens artist's paintings as works by Jackson Pollock, Mark Rothko and others. Former Knoedler President Ann Freedman named a long list of experts who she claimed had seen and endorsed the paintings before they were revealed as knockoffs. The reputations of several art experts were tarnished and at least one has been sued by a collector who bought a fake.

A bill introduced in the New York legislature in March could offer some relief to New York-based art experts. The bill aims to make it more difficult for collectors and dealers to bring lawsuits against art historians whose opinions they contest. Lawsuits have been brought against experts both for finding works inauthentic and for wrongly authenticating works that turned out to be fakes.

Even as many artists' heirs decline to perform official authentications, some continue to hold considerable influence in the marketplace.

In a recent deposition, Mark Rothko's son, Christopher Rothko, said he has twice been invited by an auction house to view Rothko paintings discovered since the publication of the Rothko catalogue raisonné. One of those paintings —which was authenticated by David Anfam, the author of the Rothko catalog—sold at Christie's for $33.7 million, Christie's said.

Last month, Christie's postponed a sale after the sisters of Jean-Michel Basquiat alleged in a federal suit that some works in the collection of Basquiat's onetime lover, Alexis Adler, were of "questionable authenticity." Six of the works had been approved by the estate's now-defunct authentication committee. Many others hadn't been evaluated.

"Now without the authentication boards, it's a real tricky situation for everybody," Ms. Adler said.

Write to Jennifer Maloney at jennifer.maloney@wsj.com

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