Gov. Kim Reynolds on Friday vetoed legislation that would have expanded Iowa’s medical marijuana program, calling for caution before increasing the potency of available products.

The Republican governor announced her decision in a statement released shortly before the start of the Memorial Day weekend.

"The health and safety of Iowans is too important for us not to get this right," she said.

Reynolds’ move slows further expansion of a medical cannabidiol program that currently allows capsules, extracts, concentrates, lotions, ointments and tinctures. Smoking medical or recreational marijuana remains prohibited in Iowa.

Had Reynolds signed it, legal medical marijuana in Iowa could have contained more THC — the chemical that makes recreational marijuana users high — than currently permitted in products made and sold in the state.

Reynolds said she based her veto on feedback from a state medical marijuana board that recommended reducing the scope of the potency changes.

“Ultimately, I believe Iowa must proceed cautiously to ensure that any expansion of our medical (cannabidiol) program is thoughtful and deliberate — particularly because Iowa’s program is in its infancy and the body of research that analyzes the efficacy of medical CBD is limited," she said.

The veto is a blow to patients of the five-year-old program, some of whom have said the existing law is inadequate in allowing them access to drugs to treat their medical conditions.

"This is not OK," said Karrie Anderson, a 47-year-old in Dallas County who has multiple sclerosis. She doesn't use the existing program because she feels it wouldn't help her, as the program is currently structured. "If you have compassion for people, you find a way to make this work."

One day before the veto, activists who supported the latest legislation submitted a petition at the Capitol to lobby Reynolds to sign the bill into law. They said it was signed by nearly 1,600 people.

More than 2,800 people have active registration cards to participate in the program, according to the Iowa Department of Public Health.

An advisory board's recommendations

The measure Reynolds vetoed would have replaced a 3% THC limit on medical marijuana products with a new measurement system: 25 grams of THC in a 90-day period to a patient or primary caregiver.

Efforts to lift the THC cap had been complicated by opposition from the Iowa Medical Cannabidiol Board. The board, primarily made up of physicians, has been leery of expanding the still-new program.

The Republican-controlled House nearly unanimously approved the bill in March, and the GOP-majority Senate finalized it on the last day of session in late April.

After the House vote, a board member resigned and said some lawmakers had misrepresented the board's position on the chamber floor. Lawmakers said that wasn't their intention.

In April, the board recommended removing the THC percentage cap and replacing it with a THC limit of 4.5 grams over a 90-day period.

In a letter to Reynolds and lawmakers, the board said the higher gram limit would allow "an extremely large amount of THC for a medical program that seeks to avoid becoming a recreational program." The board also said it could make physicians reluctant to certify patients for the program.

Despite that, Democrats and Republicans joined to approve the 25-gram limit.

What the bill would have done

Along with the change in the potency of available marijuana derivatives, the measure would have also:

Revised “untreatable pain” to “severe or chronic pain” on the list of debilitating medical conditions, a move that would have allowed more people to use the program.

Expanded the definition of a health care practitioner who can make recommendations to patients seeking treatment. Supporters believed including physician assistants and advanced registered nurse practitioners to the definition could have expanded the program’s use in rural areas.

Lifted a ban on felons becoming patients in the program.

Required state health officials to collect and evaluate data associated with the program, in an effort to better understand the benefits, risks and outcomes of patients.

Allowed patients whose conditions were terminal a waiver for unlimited THC in their cannabis products.

Reynolds said in her statement that she supported many of the provisions in the bill, including suggestions to lift the THC percentage limit. But she said the 25-gram limit would have allowed a person to consume THC levels "higher than one would typically consume even with aggressive recreational marijuana use."

"I have not been unable to discern any evidence-based justification for the specific 25-gram limit proposed in this bill," Reynolds said.

Backers 'extremely disappointed'

Patients had long lobbied lawmakers to lift the THC percentage limit, arguing the current cap forced them to buy additional products to find relief. Like representatives for the companies that manufacture and dispense the products in Iowa, they said the restrictions were wasteful, expensive and frustrating.

MedPharm, the state’s first licensed medical marijuana manufacturer, criticized the veto. Lucas Nelson, general manager for the company, said it provided the governor and the board with "peer-reviewed papers demonstrating that patients need options in their treatment."

"It is simply incorrect to state that there is not an evidence-based justification for the changes proposed in this bill," he said in a statement.

Sen. Brad Zaun, an Urbandale Republican, said while he was was "extremely disappointed" with the veto, he vowed to work with Reynolds to file revamped legislation next session.

"This will be a top priority in January 2020," he said in a statement.

“I'm very disappointed (actually, quite pissed) that Gov. Reynolds ignored the vast majority of people in Iowa who want the medical cannabis law modified to help more sick and suffering Iowans. Her veto today was simply unconscionable,” Sen. Claire Celsi, D-West Des Moines, wrote on Twitter.