On 
Cross Cast Back, if active dancers start side-by-side (as a
    Couple), they pass 
Left shoulders.  Historically, dancers
    have always passed Left-shoulders since this is a 'Cross' movement;
    however, 
CALLERLAB once 'simplified' the shoulder-passing rules,
    and many dancers were henceforth taught to pass Right shoulders.  The
    current C
ALLERL
AB definition of Trail Off (from Tandem Couples)
    states that dancers do a Half Sashay (Belle in front of Beau) &
    Peel Off, hence a 
Left shoulder pass.  Please be careful when
    dancing 
Cross Cast Back as you may encounter some dancers who
    will insist on passing 
Left shoulders and other dancers who will
    insist on passing 
Right shoulders. 
EN: 60