Accession or Accessio is method of of property under Scots property law. It operates to allow property (the accessory) to merge with (or accede to) another object (the principal), either moveable or heritable (land). Accessio derives from the Roman law concept of the same name. Other jurisdictions employ similar rules. The leading case in this area is said to be Brand's Trustees v Brand's Trustees (1876) 3 R (HL) 16.