While possession is often referred to as “nine tenths of the law”, this is certainly not the case for collections. The actual process by which an institution obtains legal title and establishes ownership of a specimen or collection of specimens is called accessioning.

Once a specimen has been accessioned by an institution, the institution becomes accountable for that fossil or collection. This has both legal and practical implications for the institution.

Accessioning is the formal process used to accept legal responsibility as a repository for, and to record a specimen as part of, a collection. It involves the creation of an immediate, brief, and permanent record for the specimen or the collection; this can be an entry in a ledger book; an index card; or a database record. This record will have a number or some other identifying code (an accession number) that links together all the objects added to the collection from the same source at the same time, and contains information about the provenance of the specimen or collection. This number is used to link the objects with this provenance information, so that will always be possible to track down the background information and prove, for example, that a specimen was legally acquired. By creating an accession record and assigning an accession number to a specimen or collection, the institution accepts custody, right, or title to it.  In some institutions this work may be done departmentally, in others it may be done by centrally by a specialist staff member, usually called the Registrar.

The Society of Vertebrate Paleontology states “Fossils and their contextual data must be accessioned and curated in an institution, the mission of which is scientific study and education in perpetuity. Fossils should be accessioned in a timely manner.” (See the full text here).

Accessioning Versus Cataloguing
Occasionally, there is confusion about the difference between accessioning and cataloging. One reason for this is that in some institutions, the method of accessioning is by cataloging – in other words, applying an institutional catalog number to the specimen and creating a catalog record is seen as asserting the institution’s right of ownership. In other institutions this single event recording is not the case, and the two terms are not used interchangeably.

Because of the legal implications associated with the process of accessioning specimens, the institution or collector must be certain (i.e., due diligence must be exercised) that:

  1. The specimens were legally acquired.
  2. The donor has a right to pass them on to the museum.
  3. The process of transferring the specimens to the museum does not breach any laws.
  4. That the relevant documentation exists to demonstrate all of the above in the event of a future legal challenge.

For an example of specific accessioning procedures, see the Accession Procedures (pdf) and associated Accession Form (pdf) from the Peabody Museum of Natural History at Yale University.