Section 360.30. Trial jury; peremptory challenge of an individaul juror

1.   A peremptory challenge is an objection to a prospective juror for
  which no reason need be assigned.   Upon any peremptory  challenge,  the
  court must exclude the person challenged from service.
    2.   Each party must be allowed three peremptory challenges.  When two
  or more defendants are tried jointly, such challenges are not multiplied
  by the number of defendants, but such defendants are to be treated as  a
  single  party.   In any such case, a peremptory challenge by one or more
  defendants must be allowed if a majority of the defendants join in  such
  challenge.  Otherwise, it must be disallowed.