HARRISBURG, Pa. — From the war on drugs to the current wave of legalization efforts, public opinion in the United States has shifted on few issues like it has with marijuana. How and why have attitudes and policies changed so drastically and rapidly?

That’s the question posed by Daniel Mallinson, associate professor of public policy and administration at Penn State Harrisburg, and Lee Hannah, professor of political science at Wright State University, in their new book, “Green Rush: The Rise of Medical Marijuana in the United States.”

“While there are a lot of good books on the topic, we didn't think anyone had centered the states as the main locus of innovation and experimentation,” Hannah said.

The use, sale and possession of marijuana is prohibited by federal law. Yet, currently, 38 states and the District of Columbia has legalized the medical use of marijuana while 24 states and D.C. have legalized marijuana for recreational use.

Mallinson and Hannah, state politics scholars who met as doctoral students at Penn State, wanted to tell a comprehensive story about medical marijuana. In their book, the authors examine the history of cannabis legalization, how medical marijuana programs started to get passed in the states, how states like Pennsylvania, Ohio and West Virginia have implemented their legalization efforts and how state policy initiatives have influenced conversations on the national level.

“You cannot understand marijuana policy in the United States, and really the changes in drug policy more broadly, without studying what’s happening at the state level,” Mallinson said.

Penn State News spoke with Mallinson and Hannah about their book, the rise of medical marijuana in America and the role Pennsylvania has played.

Q: Let’s start with some basic definitions. What is considered medical use of marijuana?

Mallinson: We focus on what we call comprehensive medical marijuana laws where there’s legal protection from state prosecution for possession and use and there’s access to product, such as through dispensaries or home grown. There are usually regulations on the industry too, like packaging and advertising regulations and tracking.

States design their programs differently. More conservative states, including Pennsylvania, adopted programs that are more structured and have more regulations and restrictions. In Pennsylvania, you must have a condition that’s on the list of conditions approved for medical cannabis and you have to go to a registered physician. Other states, like California, have looser regulations.

Q: How has the public perception of medical marijuana has changed over the years?

Mallinson: The percentage of Americans who think marijuana should be legalized has increased from 12% in 1969 to nearly 70% today. That’s a huge change and, like same sex marriage, it’s one of those issues where you see a large change in public opinion very quickly.

In the book, we talk about the image of the user and how medical use of marijuana is in some ways an easier sell. Initially, it’s the cancer patient, AIDS patient and glaucoma patient.

Then, after the war on terror era, veterans start to push for legalization for medical use for things like post-traumatic stress disorder and chronic pain. Groups of moms whose kids have severe epilepsy diseases — marijuana proves pretty efficacious in reducing seizures — who also advocate for legalization. These groups, which are broadly viewed more positively, helped push the issue into more conservative states.

Q: What were the key considerations in passing Pennsylvania’s medical marijuana law?

Mallinson: Pennsylvania has an interesting history. Medical marijuana legislation was introduced by the Democrats in the Republican-controlled state Senate in the early 2010s, but it wasn’t going anywhere until Republican state Senator Mike Folmer got involved.

He said he was swayed by a group of moms who came and talked to him about medical marijuana and the benefits for their kids. Folmer also had cancer and, at the time, people didn’t know that he had used cannabis during treatment. That was revealed later, though he maintained that wasn’t his motivation for championing medical marijuana. This also coincides with increasing opioid overdoses in the state which, combined with increasing conversation about whether cannabis could be a substitute for opioids, also helped push medical marijuana forward.

It was an uphill battle, but Folmer was well-respected and medical marijuana passed in the state Senate. It eventually passed in the House, which also had a Republican majority, and was signed into law in 2016 by Governor Tom Wolf. Getting Republicans on board in a state like Pennsylvania was important and you see that happening now with recreational marijuana legislation, which has Republican co-sponsors.

Q: You’ve mentioned that what happens on the state level affects what's happens on the national level. What role has Pennsylvania played in this larger national conversation around medical marijuana policies?

Mallinson: We have a strong supporter of legalizing cannabis for adult use in Pennsylvania’s Senator John Fetterman. He was credited with moving Wolf on the issue, who wasn’t very supportive early on, and he’s taken that to the Senate.

Pennsylvania was also one of the first states to adopt a social equity component in its medical marijuana law, which has become a cornerstone issue in the legalization of marijuana for recreational use and a major sticking point in Congress as they’re working on cannabis legislation.

Prior to legalization, you could go to jail for possession and young people of color were disproportionately affected. What happens now that it’s legal and there are rules that say you can’t be involved in the industry if you have a prior marijuana conviction? Social equity programs aim to address the inequities so that people can participate. They can also work to repair harms to communities affected by the war on drugs.

Q: Where do we go from here, both on a state and federal level?

Mallinson: On the state level, the conversation around adult-use recreational marijuana has ramped up. It has Republican co-sponsors in both chambers and Governor Josh Shapiro is open to it. It’s a big shift and there seems to be decent momentum. How long will it take? I don’t know.

On the federal level, the Department of Justice has proposed rescheduling marijuana, which would ease restrictions. It’s a big departure from past federal policy but wouldn’t legalize it or make the state programs legal. But there are still a lot of open questions and rescheduling does not solve all of the problems with state-legal marijuana. Is it inevitable that the federal government will legalize or totally decriminalize marijuana? Maybe? But Lee and I are very cautious about how fast the federal government will do anything.