A public referendum on legalising cannabis for personal use will be held by the 2020 election as part of the agreement between the Green and Labour parties.

Green Party leader James Shaw said that legalising cannabis had been party policy for 20 years, and the use of the substance should be a health issue, not a criminal justice issue.

"The prohibition model hasn't work, plus it puts the entire trade into the hands of gangs.

"If you had a regulated market, the same way we do with alcohol and tobacco, you can control the price, advertising, point of sale, quality, and run full public health education campaigns."

Shaw said public opinion on cannabis use had shifted, and a referendum on the issue by 2020 would be timely.

Other policy gains, as outlined in a letter to Green delegates for their special general meeting last night, include:

• Significant climate action, with a shift towards a net zero carbon emission economy by 2050. The specific focuses will be on: transport, energy, primary industries. The establishment of an Independent Climate Commission. Support for a shift in farming to more sustainable land use.

• Overhaul of the welfare system, ensure access to entitlements, remove excessive sanctions and review Working For Families so that everyone has a standard of living and income that enables them to live in dignity

• Significant increase in the Conservation budget

• Improve water quality and prioritise achieving healthy rivers, lakes and aquifers with stronger regulatory instruments, funding for freshwater enhancement and winding down Government support for irrigation

• Free counselling for under-25s and access to mental health services and support for everyone

• Access to education for children with special needs and learning difficulties

• Substantial progress in this parliamentary term to eliminating the gender pay gap in the public service

• Reduction in the number of students living in hardship

• Review, and adequately fund and support, the family reunification scheme for refugees

• Increase funding for alcohol and drug addiction services and ensure drug use is treated as a health issue, and have a referendum on legalising the personal use of cannabis at, or by, the 2020 general election.

Shaw said that the policy gains in the Labour-Green agreement were not a secret. The party had just not made them public yet as it was still coordinating with Labour.

New Zealand First supports a referendum on the decriminalisation of cannabis.

Shaw said there was nothing in the Labour-Green agreement that New Zealand couldn't live with, and the same applied for the Greens in relation to the Labour-NZF agreement.

He said there may be issues that would make the Greens uncomfortable, but nothing they can't live with.