Floridians will vote on medical marijuana come November, after a divided Florida Supreme Court ruled Monday that ballot language for a proposed constitutional amendment meets all legal requirements.

If at least 60 percent of voters agree, Florida could become the first Southern state to legalize use of marijuana for health-related reasons.

The ballot measure could also affect the governor's race, with Republican Gov. Rick Scott opposed to the measure and Republican-turned-Democrat Charlie Crist in favor.

The amendment, which would allow marijuana use with a doctor's recommendation and allow sale through state-regulated dispensaries, was proposed by United for Care, an advocacy group headed by Orlando attorney John Morgan, who employs Crist.

After a recent flurry of petition gathering, the group turned in enough valid signatures last week to force a vote. Court approval of the ballot — barely achieved with the 4-3 decision — was the final hurdle.

"I'm grateful that the court listened to our arguments,'' Morgan said. "Next we will begin the campaign stage. You are going to see people rise up who are the parents and siblings and spouses of really sick people who know this works and you are going to see a grass roots movement like you have never seen before in Florida.''

Scott said he would oppose the amendment.

"I have a great deal of empathy for people battling difficult diseases and I understand arguments in favor of this initiative,'' Scott said in a news release. "But, having seen the terrible effects of alcohol and drug abuse first-hand, I cannot endorse sending Florida down this path."

Attorney General Pam Bondi and other opponents have argued that the amendment's ballot summary is confusing and deceptive. The summary describes limited use only for diseases, they argued, but in fact virtually any condition approved by a doctor would qualify.

Chief Justice Ricky Polston made the same point in a dissent, writing that even someone with a sore back or test anxiety could qualify.

But the majority disagreed. The ballot summary gives voters "fair notice as to the chief purpose and scope of the proposed amendment, which is to allow a restricted use of marijuana for certain debilitating medical conditions.''

Bondi also argued that the ballot language violated Florida's single subject rule, because it made broad legislative policy determinations, established a complex regulatory system and provided so much immunity to physicians that people could not sue for fraud or malpractice.

If the measure passes, the Legislature would work out details such as how much marijuana someone could possess and how growers would be regulated.

But the court majority rejected the idea that the amendment was too complex. "It has a logical and natural oneness of purpose — namely, whether Floridians want a provision in the state constitution authorizing the medical use of marijuana as determined by a licensed physician.''

The court emphasized that citizen initiatives should enjoy broad leeway, and only language that is "clearly and conclusively defective'' should be thrown out.

Justices Barbara Pariente, R. Fred Lewis, Peggy Quince and James Perry voted in favor. Justices Charles Canady, Jorge Labarga and Polston dissented.

The concept of medical marijuana has spread to 20 states and the District of Columbia since California first legalized it in 1996. People with cancer, multiple sclerosis and other serious diseases say marijuana eases their plight in ways that prescription medicine cannot. An increasing body of science shows that chemical substances found in pot can, indeed, be beneficial.

Opponents, wary of substance abuse, say that FDA-approved, dosage-controlled prescription drugs could use those same chemicals without risking the potential for societal damage.

Though recent opinion polls indicate strong support for medical marijuana, the Republican-dominated Legislature has rejected attempts to authorize widespread medical use.

House Speaker Will Weatherford, R-Wesley Chapel, said he "respectfully'' disagreed with the court ruling and said he hoped voters would reject "this truly radical" amendment.

"Make no mistake: This is not about compassionate medical marijuana,'' Weatherford said. "This is about the Coloradofication of Florida, where the end game is a pot shop on every street corner."

Senate President Don Gaetz, R-Destin, called the amendment "a combination of cynical politics and cynical science'' designed to push Crist's prospects. "You don't have to have a doctorate in political science to figure out that John Morgan is Charlie Crist's boss and paymaster,'' Gaetz said. "The marijuana campaign is liable to bring out voters who would be more likely to vote for Charlie Crist. This is all about politics.''

Crist was quick to issue a statement: "This is an issue of compassion, trusting doctors, and trusting the people of Florida.''

Former state Sen. Nan Rich, also running as a Democrat, followed on Twitter: "I endorsed med. marijuana initiative & signed petition. Glad voters will have a chance to end suffering & bring hope to families."

Calvina Fay, executive director of St. Petersburg's Save Our Society from Drugs, said the amendment "makes a mockery out of our nation's approval process for determining safe and effective medications.''

Bondi was more subdued: "Today's ruling leaves the issue of medical marijuana in the hands of Florida's voters. I encourage every Floridian to read the full amendment in order to understand the impact it could have on Floridians."

Morgan, who said he spent about $4 million on the petition campaign, predicted that thousands of people would contribute to winning the vote.

The big push on TV and other forms of advertising would likely begin in August or September, he said.

Times staff writers Steve Bousquet and Tia Mitchell contributed to this report. Stephen Nohlgren can be reached at nohlgren@tampabay.com.