of Heffel Fine Art Auction House, that's not necessarily the case. He says auction houses can be intermediaries between buyers and curators assembling exhibits.

Does the public ever have a say?

Public outcry, widespread news coverage and legal challenges can sometimes help reverse deaccessioning decisions.

The National Gallery of Canada sparked a furore last year with its plans to deaccession and sell The Eiffel Tower, one of its two Marc Chagall oil paintings, to fund the attempted purchase of Jacques-Louis David's Saint Jérôme Hears the Trumpet of the Last Judgment, owned by a Quebec parish in need of money for repairs to a historic church. The Chagall was ultimately withdrawn from auction, but woven throughout the complicated fiasco was criticism of the gallery's leadership and lack of transparency.

The National Gallery ofCanada and its former director Marc Mayer came under fire for the decision to deaccession and auction Marc Chagall's The Eiffel Tower to fund the purchase of Jacques-Louis David's Saint Jérôme Hears the Trumpet of the Last Judgment. (Idil Mussa/CBC)

In 2009, a proposal by Brandeis University in Massachusetts to shut down its Rose Art Museum and monetize its art collection was met by a firestorm from students, alumni and artists. The public protest, plus a lawsuit from museum supporters, helped change the minds of trustees.

Widespread outrage also helped halt the 2014 auction of 85 Joan Miro paintings, which Portugal's government had seized as assets from a failed bank it had bailed out.

Some museums today are making fresh attempts to be more transparent and inviting the public to join