Section 144. Proof required

1.  In an action to annul a marriage, a final
  judgment annulling the marriage shall not be  rendered  by  default  for
  want  of an appearance or pleading, or by consent, or upon a trial of an
  issue, without proof of the facts upon which the allegation  of  nullity
  is  founded.    Plaintiff  shall  prove  that  there  has  been  no such
  cohabitation between the parties as would bar a judgment except that  in
  an  action  under  subdivision  (c)  of  section  one  hundred forty the
  plaintiff may prove instead that the mental illness still continues.
    2.   In any action, whether or  not  contested,  brought  to  annul  a
  marriage,  the declaration or confession of either party to the marriage
  is not alone sufficient as proof, but other satisfactory evidence of the
  facts must be produced.