Trump’s national security advisers warned him not to congratulate Putin. He did it anyway.

(...) Some countries where drug trafficking carries the death penalty – such as China and Iran – still have big drug problems, says John Ryan, the CEO of drug research and advocacy organisation Pennington Institute.

"The scale of people who get caught drug trafficking and the scale of the drug market proves most people think they will get away with it and are prepared to play Russian roulette."

Foreign Minister Julie Bishop was also sceptical. "I don't believe that executing people is the answer to solving the drug problem and certainly the trafficking of drugs in and out of Indonesia," she told Sky News this week.

Jeffrey Fagan, who provided expert testimony during a constitutional challenge against the death penalty in 2007, said drug offenders are prone to "hyperdiscounting".

"Their reasoning in the face of threats of harsh punishment is skewed."

If the death penalty did deter drug traffickers, it would suggest that supply would reduce in the particular country, pushing up prices. Drug use would then also fall.

But a study of the experience of Singapore, Malaysia and Indonesia between 1999 and 2005, a time when Singapore and Malaysia were executing heavily and Indonesia was not, shows that drugs were significant cheaper in Singapore and Malaysia. Drug use also rose in both countries and remained more prevalent in Singapore than Indonesia.

"During this era, 73 persons were executed in Singapore (including more than half who were drug offenders), compared to two in Indonesia," Kagan said. "Yet drug trafficking was increasing and drug prices were lower in Singapore." (...)