Amnesty International has urged Saudi authorities to stop any attempt to medically paralyse a man as a judicial punishment.
A Saudi judge is reported to have asked hospitals if it is possible to cut the spinal cord of the man, found guilty of paralysing another man in a fight.
Amnesty said intentionally paralysing someone would constitute torture.
Under Islamic law in Saudi Arabia, retribution sentences can include eye-gouging and, for murder, beheading.
"We urge the Saudi Arabian authorities not to carry out such a punishment, which amounts to nothing less than torture," said Hassiba Hadj Sahraoui, of Amnesty International.
"While those guilty of a crime should be held accountable, intentionally paralysing a man in this way would constitute torture and be a breach of its international human rights obligations."
The UK-based human rights group quoted reports that a court in the north-western town of Tabuk had approached a number of hospitals enquiring about a spinal operation.
The man in question has already been sentenced to seven months' imprisonment for the offence, which happened more than two years ago, Amnesty said.
The brother of the victim told the Associated Press news agency that the injuries had been caused in a fight involving a meat cleaver.
He said his brother, who was left paralysed and later lost a foot, had asked a judge in Tabuk to impose an equivalent punishment on his attacker under Islamic law.
Correspondents say the case highlights attempts by Saudi Arabia to balance religious traditions with a push to modernise the country.