Section 4109. Peremptory challenges

The plaintiff or plaintiffs shall have
  a  combined  total  of  three  peremptory challenges plus one peremptory
  challenge for every two alternate jurors. The  defendant  or  defendants
  (other  than  any  third-party  defendant  or  defendants)  shall have a
  combined total of  three  peremptory  challenges,  plus  one  peremptory
  challenge  for  every two alternate jurors. The court, in its discretion
  before the examination of jurors begins, may grant an  equal  number  of
  additional  challenges  to both sides as may be appropriate. In any case
  where a side has two or more parties, the court, in its discretion,  may
  allocate that side's combined total of peremptory challenges among those
  parties in such manner as may be appropriate.