Section 204. Subpoenaing hearing referees

No  officer or employee of the
  department of motor vehicles who has conducted a hearing  concerning  an
  owner  or operator of a motor vehicle or motorcycle shall be required to
  appear in any court as a witness in a civil action in which  such  owner
  or  operator  is a party except pursuant to a subpoena signed by a judge
  of a court of record, or a judge of the court in  which  the  action  is
  pending,  issued  upon an application to such judge after, at least, one
  day's notice to the commissioner  or  a  deputy  commissioner  of  motor
  vehicles.