A Supreme Court decision ordering a retrial of a Zimbabwean man acquitted of raping and murdering his niece in Christchurch in 2007 is extremely rare, says the Law Society.
George Gwaze was found not guilty in 2008.
The defence case argued that Charlene Makaza, aged 10, died of natural causes. She was HIV positive. The Crown said Mr Gwaze raped and suffocated her.
The Crown appealed against a decision by the judge in Mr Gwaze's trial to allow hearsay evidence from the defence.
The Supreme Court has now ruled that the decision led to a substantial miscarriage of justice.
Law Society criminal law committee convenor Jonathan Krebs says the case is a very rare exception to the legal precedent of double jeopardy.
Although lawyers will be interested in the Supreme Court's reasoning, he said the public should not be unduly worried about acquittals.
The retrial is not expected to begin until next year.
Nigel Hampton, QC, says the retrial is a legal first in New Zealand.
He says the move away from the Privy Council in Britain as the country's highest court, to a Supreme Court has made such challenges more accessible.