Deaccessioning, the process of disposing, selling or trading objects from a museum collection, is not undertaken lightly in most museums. There are ethical issues to consider since many donors of objects typically expect the museum to care for them in perpetuity. Deaccessioning of an object in a collection may be appropriate if a museum has more than one example of that object and if the object is being transferred to another museum. It may also be appropriate if an object is badly deteriorated or threatening other objects.
The decision to deaccession includes two parts. These are making the decision to deaccession and deciding the method of disposal. Generally, first choice is to transfer an object to another use or division in a museum, such as deaccessioning a duplicate object from a permanent collection into a teaching collection. Second choice is to transfer the object to another institution, generally with local institutions having priority. The American Association of Museums and other regional associations often operate lists or boards to help facilitate such transfers. Last choice is sale on the open market. Open market sales are generally expected to take place at auction rather than through private sale, and are typically most common in art museums due to the high monetary value of art collections.
A controversial example occurred when the last remaining complete Dodo mount in a museum collection at Oxford University was deaccessioned due to its deterioration in 1775. Another case was the sale of a J. M. W. Turner painting in the collection of Royal Holloway, University of London to the Getty Museum to fund the maintenance of the building, despite the fact that the original benefactor had expressly requested that the collection be kept intact.
Many ethical guidelines for deaccessioning require that the funds generated by disposing of collection items be used only to increase or maintain the remaining collection. For example, the International Council of Museums (ICOM) Code of Ethics states that:
Money or compensation received from the deaccessioning and disposal of objects and specimens from a museum collection should be used solely for the benefit of the collection and usually for acquisitions to that same collection .
In the United Kingdom, guidelines governing deaccessioning and other ethically difficult issues can be found in the Museums Associations Code of Ethics. In the United States, the guidelines on these matters are issued by the American Association of Museums.
The American Association of Museums Code of Ethics takes the position that in no event shall they [deaccessioning proceeds] be used for anything other than acquisition or direct care of collections.
Other museums may have additional restrictions on the use of funds from deaccessioning. For example, at some museums funds from deaccessioning a work of art can only be used to purchase a work of similar style or period (for example, funds from selling a 20th century American print could not be used to buy a 17th century Italian painting) and the name of the donor of the sold work remains associated with the purchased artwork.