"Some procedures at a trial provide fundamental protection against
wrongful conviction, but, in conformity with the passage already
quoted from the judgment of Dixon CJ in Maxwell v. Murphy, this
ordinarily provides no basis for regarding them as having a
retrospective operation simply because the trial concerns events
and transactions past and closed. The fact that such procedures
are important does not alter the way in which they operate and, if
they operate so as to affect no existing rights or obligations but
merely the way in which those rights or obligations are to be
contested in court, then they do not fall within the presumption
against retrospectivity. Fundamental rights, irrespective of
whether they should be classified as procedural or substantive,
will almost invariably be reflected in the common law and the
protection against statutory interference with them, whether
prospective or retrospective, lies in another presumption. That
is the presumption that the legislature does not intend to affect
basic common law doctrines unless it expresses its intention in
the clearest of terms: Potter v. Minahan; Baker v. Campbell;
Sorby v. The Commonwealth; Hamilton v. Oades."