Testing Mrs. Gardner's will

It's like a pillow fight at the Tavern Club. On one side, you have fuddy-duddy preservationists, High Church Episcopalians, and serious art aficionados worried about the future of a genuine Boston treasure - the Isabella Stewart Gardner Museum.

Opposing them: museum president and Tavern member Anne Hawley, her moneybags board president Barbara Hostetter (think: cable TV fortune) and "Renzo," the glib, imperious Genoa-based starchitect Renzo Piano, who proposes to turn "Mrs. Jack's" Fenway jewel into a "shopping mall." Or so his detractors say.

But first, the will. Both sides acknowledge that Piano's grandiose scheme cannot proceed under the terms of Gardner's 10-page will, filed in 1924. In a nutshell, Mrs. Gardner forbade any monkeying around with her gorgeous, Italianate palazzo and its contents. So last month the museum's lawyer, Stephen Kidder of Hemenway & Barnes, asked the attorney general to permit a "reasonable deviation" from Mrs. Gardner's wishes.

According to the museum's filings, Piano needs to punch through a cloister wall, fiddle with a sarcophagus, and raze a lovely carriage house to mount his multi-story, glassine vision next to the existing museum. (One of Piano's early proposals suggested surrounding the museum with a canal.) In court papers and in public appearances, Hawley insists the Piano-designed extension is desperately needed to relieve overcrowding of staff and visitors at the museum. "If [the museum] remains as it is, it's going to die," she told an audience at the Boston Public Library last week. "It's our responsibility to keep the museum alive."

Inconveniently, some people disagree. The Friends of Mission Hill - these would be the fuddy-duddy preservationists - have retained attorney Lynne Viti, a Wellesley College professor, to do battle with Kidder. "Our position is, 'Hey, wait a minute, building a 60,000-square-foot structure is not a little deviation from the will,' " Viti says. "That is completely going against this very eccentric and unique woman's vision. It is just too extreme."

Mrs. Gardner's will has been challenged before. The museum was granted two previous deviations, for minor requests. More recently the state pushed back against a proposed exhibit of Venetian art in the storied Tapestry Room. That exhibit was relegated to the fourth floor.

Here's the part I love: If the parties can't reconcile their differences, the will awards the whole kit and kaboodle to . . . Harvard! "If [the Trustees] shall at any time change the general disposition or arrangement of any articles . . . of said Museum at my death," Mrs. Gardner wrote, "I give the said land, Museum [and contents] . . . to the President and Fellows of Harvard College."

The World's Greatest University gets the World's Greatest Art Museum? "Not a chance," opines one lawyer in the case. Harvard says it supports the proposed deviation.

I have some bad news for my High Church brothers and sisters: Things are looking bleak. Last Friday the AG's office said the museum could sidestep the will "to continue to carry out its responsibilities to preserve and protect the mission of the Isabella Stewart Gardner Museum as envisioned by the founder." The Supreme Judicial Court is the ultimate arbiter. Viti's opposing brief is due next week, and what happens next is anyone's guess.

Why a pillow fight? Because everyone is acting disturbingly civil. All the parties praise the patience and expertise of the attorney general's expert, Johanna Soris, and Viti says she has had only "polite exchanges" with Kidder. "There's a lot of becoming gentlemanliness here," she says. How very Boston.

How much will this cost, and does the Gardner have the dough? Hawley refuses to discuss finances. (I'm told $150 million.) "This is going to be a costly project," Viti says. "What happens if they don't have the financing in place? Then you will have lost something you can never restore."

I wouldn't bet against the Gardner on this one. So brace yourself for Renzo's glossy vision of Las-Vegas-on-Palace Road. Maybe it's time for a change.

Alex Beam is a Globe columnist. His e-dress is beam@globe.com.