Former Prime Minister Helen Clark has been appointed to the Global Commission on Drug Policy.
The commission is one of the world's leaders on drug research and law and advocates for a health-based approach to drug policy.
New Zealand Drug Foundation executive director Ross Bell said her appointment was a "real coup".
"The mana of the commission will be further strengthened by [Miss] Clark's appointment.
"It's likely New Zealand will find ways to involve her in the domestic discussions we will soon be having about health approaches to drugs and cannabis law reform."
Miss Clark worked on the issue of drug policy during her time with the United Nations.
She left her role as head of the UN Development Programme earlier this year after failing in her bid to become the UN Secretary General.
The commission is chaired by former Swiss president Ruth Dreifuss. Its members also include the former heads of Colombia, Poland and Greece.
Miss Clark is the 25th member.