NEW YORK (NYT NEWS SERVICE).- For more than three decades, Marc Restellini’s life has been very much about his study of Amedeo Modigliani, the Italian painter known for his elongated, slender faces and figures.

He has organized exhibitions of Modigliani’s work in spots around the world and in the 1990s began his own magnum opus: a catalogue raisonné, or a definitive compendium, of Modigliani’s work.

He has been exhaustive in authenticating the artist’s work because Modigliani, whose paintings often sell for millions of dollars, has been a favorite of forgers. So to document their authenticity, Restellini, a French art scholar, has worked to persuade owners to submit their paintings for testing, sampled the paint, analyzed the works with infrared photography and magnetic resonance, and sought documents from family members of Modigliani’s original collectors.

But now, months before the first volumes of Restellini’s catalogue raisonné are expected to be published, he says in a federal copyright lawsuit filed in Manhattan this week that he believes a nonprofit organization in New York, the Wildenstein Plattner Institute, is planning to make some of his research publicly available.

“The law allows Mr. Restellini, and only Mr. Restellini, to determine how, when, and where to disclose the results of his years of research and his scientific discoveries about the works of Modigliani,” his lawyer, Daniel W. Levy, said in a statement.

Restellini’s lawsuit against the institute asserts that it is in possession of roughly 89 boxes and various other containers of research materials that he had amassed over the years and that are rightfully his. The lawsuit accuses the nonprofit of holding this research “hostage.”

The Wildenstein Plattner Institute, however, says the records are theirs.

Calling the lawsuit a “publicity stunt,” the nonprofit organization’s lawyers said in a statement that the institute’s files regarding Modigliani “do not belong to Mr. Restellini.” The statement said the institute is legally within its right to “share its Modigliani archives with the public in furtherance of its charitable mission.”

The research materials are with the institute because, for about 17 years, according to the lawsuit, Restellini’s work was supported by an older institute, the Wildenstein Institute, an art history research center based in Paris and operated by the Wildenstein family, a French art-dealing dynasty that dates back four generations. Restellini used the institute as a workspace and had access to its library and storage facilities.

In the late 1990s, Daniel Wildenstein, then the family’s patriarch, had offered to facilitate Restellini’s work on the catalogue raisonné and to participate in its eventual publication, the lawsuit said. But in 2014, after Wildenstein had been dead for more than a decade, his son Guy told Restellini that the institution would no longer facilitate his research, it said.

The lawsuit does not address the reason for that decision.

In recent years, the lawsuit said, as the Wildenstein Institute wound down its operations, it transferred the archives to a new nonprofit organization, the Wildenstein Plattner Institute — which is dedicated to the compilation of catalogues raisonnés.

Lawyers for the Wildenstein Plattner Institute would not elaborate on why they believe the Wildenstein Institute held clear title to the archive.

The Wildenstein Plattner Institute said this year that it had digitized all of those gifted archives; Restellini’s lawsuit seeks not only to prevent them from publishing the material but to destroy any digital copies that they have.

In recent years, a widening circle of scholars and artists’ foundations have refused to offer opinions on the authenticity of works of art for fear of being sued by buyers or sellers unhappy with their conclusions. The inclusion or exclusion of a work in a catalogue raisonné can have a similar effect on the value of a work. Restellini has said he has been threatened after refusing to authenticate a work.

The authenticity issue is particularly fraught in the market for Modigliani. Although the artist only lived until 35, he was prolific and sometimes, to pay his bills, he gave away and sold paintings and drawings, without documenting their creation or to whom they had been sold or gifted.

Restellini’s catalogue raisonné is believed to be the sixth inventory created of the artist’s work. The first volumes of it are expected to be published this winter. It promises the inclusion of dozens of previously unidentified Modigliani works and excludes those that are suspected of not being entirely composed by the artist.

In seeking to demonstrate the importance of his undertaking, the lawsuit highlights a particular work that Restellini contends is an altered Modigliani but was sold by an auction house twice as a work done completely by Modigliani’s hand. Restellini’s lawsuit contends the auction house relied on an earlier, less precise catalogue raisonné in making that determination.

© 2020 The New York Times Company