authorities.  Such court stimulation of a review of the law in a particular area can be valuable in areas in which there might otherwise have been little pressure for change.  The decision of our  Court  of  Appeal  in  Quilter  v  Attorney-General⁶  certainly  stimulated  discussion  of  the issue of same-sex marriages. Sometimes  the  courts  are  invited  to  effect  a  significant  change  or  development  in  the  law.   Pressing  factual  circumstances  and  compelling  argument  may  point  to  injustice  in  the application of established principle.  Consideration then must be given to the issue whether to leave  the  matter,  duly  highlighted,  for  legislative  attention  or  whether  to  change  legal principle by judicial decision.  Which course is adopted depends on many factors.  I mention a few.  Much depends on the nature of the issue.  If it is in a field of law largely developed by the  courts  there  will  be  less  reluctance  to  make  changes.    If  it  is  in  an  area  where  the implications of any change are unclear so that the issue would benefit from wider research and analysis than the courts are equipped to employ, there will be great reluctance to make any  change.  The  existing  principle  may  be  long-standing  and  underlie  entrenched practices and commitments.  There may be circumstances of urgency linked with the recognition that it will always be open to the legislature to overrule or modify the change.  It may be that on close analysis the existing principle is not soundly based.  There may be discernible policy in legislation in related areas indicating a direction for change.  The existing principle might rest on  superseded  social  values.    There  might  be  current  law  reform  work  that  is  expected  to review the existing principle.    Weighing  these  and  other  relevant  factors  can  result  in  differing  judicial  views.    This  is evident in a number of recent decisions of the New Zealand Court of Appeal. In 1983 the Court considered whether a method of medical treatment should be capable of attracting patent protection.⁷  It was said on the one side that the grant of monopoly rights in this area could interfere with the ability of the medical profession to provide patients with the best  appropriate  treatment.    On  the  other  side  it  was  contended  that  it  was  anomalous  to exclude  from  protection  meritorious  inventions  in  just  one  field  when  the  definition  of invention in the Patents Act drew no distinction so that current practice was unsupportable.   6 [1998] 1 NZLR 523 7 Wellcome Foundation v Commissioner of Patents [1983] NZLR 385