The unanimous decision delivered by the court on Wednesday renders her fit to continue to face her extradition trial, which is pending a ruling.

Leifer is wanted in Australia for 74 charges of rape and child abuse from her time as principal at Melbourne's Adass Israel School.

Three Melbourne sisters' who were allegedly abused by Leifer, who fled to Israel after allegations arose in 2008, have been fighting to bring her back to Australia for almost a decade.

After countless delays in Israeli courts, the extradition hearing commenced in July, on the basis Leifer was mentally fit to stand trial, as sanctioned by the court.

But her lawyers once again filed an appeal, even with the trial ongoing and a final psychiatric assessment already heard.

Longtime victim supporter Manny Waks released a statement following the appeal being rejected saying it was an expected decision.

"It's been clear to practically everyone following this case - including countless experts - that Leifer has taken the Israeli judicial system for a major ride," Waks wrote.

"In their ruling, even the judges said that proceedings had dragged out 'much beyond what is reasonable."

The Zionist Federation of Australia President Jeremy Leibler stressed to AAP after the decision that past evidence introduced to the courts had always shown Leifer was faking mental incapacity.

"This unanimous rejection of her appeal by the Supreme Court helps restore faith in a system that allowed Leifer's alleged victims to wait for so long," Leibler said.

"It is past time to bring Leifer back to face justice in Australia."

The Jerusalem District Court decision on her extradition is set to be announced on September 21.

Leifer's lawyers, however, will have an opportunity to appeal.

Australian Associated Press