Wordnet 3.0
NOUN (1)
1. 
 (law) the principle that an act done at a later time is deemed by law to have occurred at an earlier time; 
- Example: "his attorney argued for the relation back of the amended complaint to the time the initial complaint was filed"[syn: relation back, relation]
WordNet (r) 3.0 (2006):
relation back
    n 1: (law) the principle that an act done at a later time is
         deemed by law to have occurred at an earlier time; "his
         attorney argued for the relation back of the amended
         complaint to the time the initial complaint was filed"
         [syn: relation back, relation]