In preparation for New Zealand’s September 19 referendum on cannabis, all sides of the debate are sharpening their lines of argument.

Often, both the proponents and detractors of cannabis reform point to examples in the United States to bolster their position. But in the whirlwind of online debate, fact-checking is more of an option than a prerequisite, unfortunately.

Some of the best data on the effects of cannabis reform does come from the US. Many states have had medical marijuana laws since the 1990s and legalisation of nonmedical use since 2012.

This page is meant to be a touchstone for anyone looking for speedy – and accurate – information on what exactly is happening in the US. This project has pulled all the relevant cannabis reform data from each of the 50 states, drawing on a range of sources at both the federal and local levels.

The resulting data is loaded into the map of the US below.

Please, click around to learn more.

Key insights:

The US is essentially 50 real-time, parallel public policy experiments. While many federal laws apply nationwide, local US state governors have plenty of flexibility in setting their own policy.

Some US states began dealing with cannabis 100 years ago, while others have only just tabled the issue in the last few years. As of December 2019, 11 states and the District of Columbia (DC) have legalised cannabis for adult nonmedical use while 33 states and DC have legalised cannabis for medical purposes.

The debate about whether legalisation has more benefits than costs has picked up steam across the country: a Gallup poll conducted in 2018 found that two out of every three Americans support legalising cannabis.[1]

And cannabis has also grabbed the attention of big business. Cannabis, or marijuana, is being used by the cosmetic, pharmaceutical and food and beverage industries. The US cannabis market size was valued at $US11.3 billion in 2018 and is expected to follow a compound annual growth rate of 14.5% out to at least 2025, according to a study by Grand View Research.[2]

At the close of 2019, 33 US states now allow marijuana for medical, recreational or both purposes. The 2018 Farm Bill, which legalised the cultivation and sale of hemp and hemp oil, has helped cement the idea for many governors that it is time to rethink cannabis policy.

However, the market is not quite mature enough yet. The Bank of New York Mellon, one of the largest custody and clearing banks in the world controlling $US35.5 trillion in assets, announced in October 2019 it would stop accepting positions or trading with US marijuana-related businesses citing concerns with the standards of anti-money laundering processes.

And on measurements such as violent or property crime in states which have legalised cannabis, the data shows a downward trend in those crimes tends to begin before the decriminalisation of cannabis comes into force.

Many academics and research institutes have looked into the relationship of law changes and a drop in crime. So far, a 2019 study by Ruibin Lu, et al, showed “no statistically significant long-term effects of recreational cannabis laws or the initiation of retail sales on violent or property crime rates”[3] in the two US states which first legalised the drug – Washington and Colorado. Those two states have the greatest volume of data.

According to a study by Yu-Wei Luke Chua and Wilbur Townsend, the authors could find no causal effects of medical marijuana laws on violent or property crime at the national level. The two also found no strong effects within individual states, except for in California where the medical marijuana law reduced both violent and property crime by 20%.

The authors also note there is no way to tell if increased use of cannabis will affect crime rates over time.

The interactive map below displays many of those trend lines clearly and outlines how the 50 states have dealt with cannabis.

Interactive map of cannabis reform across the US:

Background on New Zealand's cannabis referendum 2020

The New Zealand cannabis referendum will be non-binding on the question of whether to legalise the sale, use, possession and production of cannabis.

It will coincide with the 2020 General Election and also a euthanasia referendum on September 19.

Marijuana is currently illegal in New Zealand and is regulated by the Misuse of Drugs Act 1975, making unauthorised possession of marijuana a crime. This law was amended in 2018 to allow for the broader use of medical marijuana to provide access to the drug for terminally ill patients in the last 12 months of life. In 2019, an amendment to the Act was passed which gave Police greater discretion for prosecuting the recreational use of the drug while punishing those who illegally supply rather than use the drug.

The referendum is simply a 'yes' or 'no' vote based on whether the voter supports the proposed Bill. Upon passing with 50% of the 'yes' vote, regulation may be similar to US states which also have full legalisation. The bill legalises marijuana under certain preconditions such as restricting access to those under the age of 20. It also will regulate the maximum amount to be consumed at 14 grams, licensing premises will be able to consume and sell and tax revenue will be generated through authorised cannabis businesses. The Bill also focuses on "harm reduction" and will "seek to lower the overall use of cannabis" while simultaneously aiming to reduce commercial activity in the black market.