A former Adelaide teacher will be asked to defend child sex charges after failing in an appeal to the High Court.
The man, who can't be identified, was found to have no case to answer in a trial before the South Australian District Court on a charge of persistent exploitation of a child dating back to 1977.
But the judge's decision, which came at the close of the prosecution case, was overturned by the SA Court of Criminal Appeal which ordered the matter be returned to the District Court to hear further evidence.
The High Court on Wednesday dismissed a bid by the man to overturn the appeal court's ruling.
In the District Court case, the trial judge found that the prosecution had failed to identify two or more proved sexual offences over a given period of time, which were necessary to sustain the charge.
The trial heard the man would regularly visit the victim's home, sometimes to help with school work.
His offending was alleged to have occurred between 1977 and 1982, starting when the victim was about 12 or 13 years old.
The appeal court found that, taken at its highest, the evidence of the victim was capable of proving two or more offences over a period of three or more days.
In its judgment on Wednesday, the High Court ruled that it was sufficient for a judge or a jury to accept that offences occurred every night or every weekend over a given period, without identifying particular occasions.
© AAP 2017