More than 140 of Australia's leading law professors, deans and academics have signed a petition pleading with Indonesian President Joko Widodo to use his constitutional powers to spare the lives of the Bali nine pair, Andrew Chan and Myuran Sukumaran.

Professor of Criminal Justice at the University of Sydney, Mark Findlay, said the response from the legal fraternity over the past 24 hours has been "astonishing in its commitment and its concern".

"We are not lecturing the Indonesians, but rather we want to commend their prison system which seems to have assisted in the remarkable rehabilitation of our two fellow citizens," he said.

The petition says the academics seek the Indonesian president's mercy, "not as critics of Indonesia, or its legal system, nor of Indonesia's right to take the strong but ultimately humane action against drug traffickers who bring misery and addiction to many".

"While opposing capital punishment as cruel and inhuman we also condemn the exploitation which the drug trade represents," the petition says.

The academics say the Republic of Indonesia has earned growing respect and approval among the international community for its demonstrated commitment to protecting human rights, and has made an important contribution to human rights protection globally as a member of the United Nations Human Rights Council.

"President Widodo himself has been a strong advocate for human rights, with the advancement of human rights a central plank in his 2014 presidential election campaign," the academics say.

"The deaths of Chan and Sukumaran would be a tragedy for them, and their families, while not addressing the underlying causes of the drug trade in Indonesia.

"In contrast, sparing the lives of these two young men, who have demonstrated remorse for their crimes and have been rehabilitated during their lengthy imprisonment, would be a signal of strength and mercy, an affirmation of President Widodo's deep commitment to human rights.

"Presidential clemency would serve as a turning point and opportunity for Indonesia to achieve its overriding national interest – combating the drug trade. It would do so by being a rallying call for Australia and other countries in the region to develop and implement an effective regime to stamp out the damaging drug trafficking trade once for all."

The petition includes the following statement signed by more than 140 academics:

"As lawyers, concerned academics and professionals, we join to speak out against the impending and tragic execution of our fellow citizens in Indonesia.  We do not see this punishment as either an issue of national sovereignty or of just desserts.

"The Australian police gave up these two men to a capital punishment jurisdiction as part of an operation which could have led to prosecutions and trials in Australia where the death penalty is not an option.

"Capital punishment is said to be qualified by mercy. In ultimately deciding on clemency we believe the Indonesian Government should give the strongest consideration to the remarkable rehabilitation history of the two condemned. In opposing these executions we are not seeking to criticise the judicial process of another country.

"However, we want to see justice tempered with humanity.  Right-minded Australians share the abhorrence of misery and addiction associated with drug abuse and the shameful trafficking trade. That said, nothing in our view can justify the killing of two men in circumstances such as these.  At this final hour we add our voices to the calls for the death sentences to be commuted and for Australia and Indonesia to join in other ways to fight the harmful health consequences of drug abuse in all its forms."