Section 71

A new trial shall not be granted on the ground of improper admission or rejection of evidence unless in the opinion of the Federal Court some substantial wrong or miscarriage of justice has been thereby occasioned; and if it appears to the Federal Court that the wrong or miscarriage affects part only of the matters in controversy, or some or one only of the parties, the Federal Court may give final judgment as to part thereof, or as to some or one only of the parties, and direct a new trial as to the other part only, or as to the other party or parties.

A new trial may be ordered on any question without interfering with the finding or decision of the court below upon any other question.