23635.  When an allegation of a violation of Section 23152 is
dismissed by the court, an allegation of a different or lesser
offense is substituted for an allegation of a violation of Section
23152, or an allegation of a separate conviction is dismissed or
stricken, the court shall specify on the record its reason or reasons
for the order.  The court shall also specify on the record whether
the dismissal, substitution, or striking was requested by the
prosecution and whether the prosecution concurred in or opposed the
dismissal, substitution, or striking.
   When the prosecution makes a motion for a dismissal or
substitution, or for the striking of a separate conviction, the
prosecution shall submit a written statement which shall become part
of the court record and which gives the reasons for the motion.  The
reasons shall include, but need not be limited to, problems of proof,
the interests of justice, why another offense is more properly
charged, if applicable, and any other pertinent reasons.  If the
reasons include the "interests of justice," the written statement
shall specify all of the factors which contributed to this
conclusion.