Principal challenge
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
A challenge of a juror for a cause which carries with it, prima fade, evident marks of suspicion either of malice or favor; as that a juror is of kin to either party within the ninth degree ; that he has an interest in the cause, etc.
3 Bl. Comm. 363.
A species of chnilenge to the array made on account of partiality or some default in the sheriff or his under-officer who arrayed the panel.