Barriers to accessing medicinal cannabis will be scrutinised during a parliamentary inquiry which will look at how Australia regulates the drug.
The Greens won support for the inquiry 35 votes to 31 on Thursday, with Labor and crossbench senators helping the minor party to defeat the government.
The Senate's community affairs committee will look at the suitability of medicinal cannabis for government subsidies through the Pharmaceutical Benefits Scheme.
It will also compare Australia's regime to other countries and investigate training and education of doctors in relation to the treatment.
The committee is due to report on February 12 next year.
Australian Associated Press