translate English to French: Sopinka and Lederman also quote, with approval, the  rationale for this rule stated in Wigmore, Evidence  (Chadbourne rev. 1976), #1873 at 672: "... first, the possible unfairness to an opponent who  has unjustly supposed that the case in chief was the  entire case which he had to meet, and, second, the  interminable confusion that would be created by an  unending alternation of successive fragments of each  case which could have been put in at once at the  beginning."
672) : [TRADUCTION] [...] d'abord le risque d'injustice à l'endroit   d'une partie adverse qui a supposé à tort que la preuve   principale renfermait la totalité des éléments de preuve auxquels   elle devait répondre et, deuxièmement, la confusion interminable   qu'engendrerait une alternance sans fin de fragments de la preuve   de chaque partie qu'il aurait été possible de rassembler dès le   départ.