Section 721. Review of certain assessments

In any proceeding wherein
  the assessment being reviewed has been challenged on the grounds that it
  is unequal and where the real property is or  has  been  improved  by  a
  residential  structure  containing no more than three dwelling units, at
  least one of which is  occupied  by  the  petitioner,  the  court  shall
  further  permit  the  introduction  of  any evidence deemed relevant and
  material to establishing the relationship between the assessed value and
  the market value of such real property notwithstanding any provision  of
  law to the contrary.
    * NB Expired May 15, 1981