grandriver/iStockBy Ivan Pereira, ABC News

(NEW YORK) — In the last four months, five states have legalized recreational marijuana, meaning now 30% of the country allows its adult residents to possess and use cannabis.

At least two more states are poised to be added to that list following the passage of cannabis legalization bills this year.

Marijuana policy experts and advocates say this national trend is indicative of a shift in Americans’ perspectives on marijuana.

Arguments from elected officials and voters that centered around perceived dangers of marijuana substance abuse or a rise in criminal activities have quelled as evidence has grown to show there are economic, social and health benefits from a state regulated cannabis industry, according to Mason Marks, a law professor at Gonzaga University and a fellow-in-residence at Harvard Law School’s Petrie-Flom Center for Health Law Policy, Biotechnology, and Bioethics.

“It’s turning out to be very antiquated,” Marks said of past opposition to legalizing marijuana.

Marks and other experts say there will be stronger legalization efforts in the near future. However, they noted there would still be an uphill battle before the country sees any true national repeal of its marijuana laws.

As of April 7, 15 states have legalized recreational and medical marijuana through voter ballot initiatives or state bills. The New Mexico and Virginia state legislatures passed bills this session that would repeal their respective prohibitions on cannabis and are awaiting signatures from their governors.

State leaders have led their legalization efforts by emphasizing how a regulated market could help boost their coffers in a post-pandemic economy and acknowledging the decades of social justice issues that were created by current and previous drug laws.

When New York Gov. Andrew Cuomo signed the state bill to legalize marijuana last week, he touted the estimated $350 million in annual tax revenues that the bill would bring and said it would “right the wrongs of the past by putting an end to harsh prison sentences.” This was in sharp contrast to four years ago, when Cuomo told reporters he was opposed to legalizing marijuana, calling it “a gateway drug.”

“As of this date, I am unconvinced on recreational marijuana,” Cuomo said in February 2017.

Marks said Cuomo’s changing sentiments are in line with the rest of the country. Since 2012, when Colorado and Washington became the first states to legalize and regulate, national support for ending cannabis prohibition has risen from 48% to 68%, according to a February Gallup poll.

Steven Hawkins, the executive director of the nonprofit advocacy group the Marijuana Policy Project, told ABC News he believes the near-decade of legalized marijuana in the country has shown people that decriminalizing and regulating marijuana doesn’t result in bad consequences for communities.

A study released in 2019 by Washington State University found “no statistically significant long-term effects of recreational cannabis laws, or the initiation of legal retail sales, on violent or property crime rates,” in Washington state or Colorado.

Hawkins said more Americans are also realizing the decades of unequal treatment brought by state drug laws and are more vocal in rectifying them. He noted that there were over 650,000 arrests for cannabis-related offenses last year, 90% of which were for possession, and the majority of those arrests were of minorities.

“I think most people have come to realize that cannabis has not been a gateway drug but a gateway to the criminal justice system,” Hawkins told ABC News.

Hawkins said there will be more pressure on other states to change their laws, but warned that there will still be more work ahead, even in places where voters approved legalization measures.

In South Dakota, 225,260 voters, or roughly 54% of the electorate, voted in favor of a constitutional amendment that legalized recreational marijuana, according to state election results. Four other states also passed ballot measures on Election Day that legalized marijuana.

The South Dakota ballot measure, however, was challenged in a lawsuit filed by state officers on behalf of Gov. Kristi Noem.

In February, Circuit Judge Christina Klinger ruled in favor of the plaintiffs, stating the measure violated the state’s single-subject rule and was a revision of the constitution rather than an amendment, and the decision is pending an appeal.

“Governor Noem swore an oath to protect both the South Dakota and United States Constitution. Amendment A was passed in an unconstitutional fashion, so as part of her duty as governor, she is supporting the lawsuit challenging the amendment,” Ian Fury, a spokesman for Noem, said in a statement to ABC News.

Hawkins said the suit is undermining the will of the voters, who he noted mostly voted for Republicans in the congressional and presidential race. He added that he believes the suit won’t dissipate strong support from South Dakotans.

“If anything, it would slow down the process,” Hawkins said of the legal action taken by opponents in South Dakota. “What South Dakota shows is the electorate crosses political lines when it comes to cannabis.”

Marks said the ultimate battle will come in Washington, D.C. As more states legalize marijuana, Congress will have to come up with legislation that addresses the national drug laws.

However, there is still some work to be done on the federal level, according to Marks.

President Joe Biden said there needed to be more recreational cannabis legalization research before he could fully support it.

In an interview with Politico last week, Senate Majority Leader Chuck Schumer has said he wants to see a bill introduced, even if the president isn’t fully on board.

“I want to make my arguments to him, as many other advocates will,” Schumer told Politico. “But at some point, we’re going to move forward, period.”

Marks said he thinks it is concerning that the president and congressional leaders aren’t in sync on the issue. He predicted they’re going to have to make a concerted effort to address the growing support and success of legalized marijuana in the states.

“It really is a public health consideration, whether the state legislators or other leaders say it or not,” he said. “People are going to use this no matter what, and we’ve got to do make sure it’s done safely.”

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