Japan prides itself on having a low tolerance for guns and drugs, but a tiny political party has become the first to adopt an election pledge of scrapping the research ban on medical use of marijuana.

Proponents say such use could ease cancer-related pain, prevent dementia and cut soaring medical costs. But the government says its effectiveness has not been proved and worries about the social harm that weaker controls could bring.

Owning and growing marijuana remains strictly against the law here despite the trend in other advanced countries, such as Canada and the United States, to free up medical use.