Exhumation

Exhumation is the act of digging up, especially a corpse. This is most often done to relocate a body to a different burial spot. 
Families may make this decision to locate the deceased in a more pertinent or convenient place. In shared family burial sites (e.g. a married couple), if the previously deceased person has been buried for an insufficient period of time the second body may be buried elsewhere until it is safe to move it to the requested grave. 
In most jurisdictions a legal exhumation usually requires a court order or permission by the next of kin of the deceased. Also in many countries permits are required by some governing agency like the board of health in order to legally conduct a disinterment.