John Elderfield, former chief curator of painting and sculpture at the Museum of Modern Art, remembers the days when scholars spoke freely about whether a particular work was genuine.

They were connoisseurs, this was their field of expertise, and a curator like Kirk Varnedoe, Mr. Elderfield's predecessor at the Modern, would think nothing of offering his view of a drawing attributed to Rodin, his specialty.

"He was qualified to do it and felt he had a moral obligation to do it," Mr. Elderfield said.

But when the owner of a painting attributed to Henri Matisse recently asked Mr. Elderfield for his opinion, he demurred. He worried he could be sued if he said the painting was not a real Matisse.

Mr. Elderfield is hardly alone in feeling that art's celebrated freedom of expression no longer extends to expert opinions on authenticity. As spectacular sums flow through the art market and an expert verdict can make or destroy a fortune, several high-profile legal cases have pushed scholars to censor themselves for fear of becoming entangled in lawsuits.

The Andy Warhol Foundation for the Visual Arts, the Roy Lichtenstein Foundation and the Noguchi Museum have all stopped authenticating works to avoid litigation. In January the Courtauld Institute of Art in London cited "the possibility of legal action" when it canceled a forum discussing a controversial set of some 600 drawings attributed to Francis Bacon. And the leading experts on Degas have avoided publicly saying whether 74 plasters attributed to him are a stupendous new find or an elaborate hoax.

The anxiety has even touched the supreme arbiter of the genuine and fake: the catalogue raisonné, the definitive, scholarly compendium of an artist's work. Inclusion has been called the difference between "great wealth and the gutter," and auction houses sometimes refuse to handle unlisted works. As a result catalogue raisonné authors have been the targets of lawsuits, not to mention bribes and even death threats.

"Legal cage rattling was always part of the process," said Nancy Mowll Mathews, president of the Catalogue Raisonné Scholars Association. But the staggering rise in art prices has transformed the cost-benefit analysis of suing at the same time that fraud has become more profitable, she said.

Fears of being sued may even lead to changes in the nature of catalogues raisonnés, Ms. Flescher added. She pointed to recent decisions by the Calder and Lichtenstein foundations and the Noguchi Museum to move their cataloging efforts online and label them as "works in progress."

"What we are presenting is a combination of completed research and research pending," said Shaina D. Larrivee, project manager of the Isamu Noguchi catalogue raisonné. "We are very clear that 'research pending' does not guarantee inclusion in the final catalogue raisonné, and that we have the ability to remove artworks if new information comes to light."

To read the complete article, see:In Art, Freedom of Expression Doesn't Extend to 'Is It Real?'(www.nytimes.com/2012/06/20/arts/design/art-scholars-fear-lawsuits
-in-declaring-works-real-or-fake.html)