Vermont was set to become the ninth state to legalize marijuana for recreational purposes. But on Wednesday, the Republican governor, Phil Scott, vetoed the bill.

The bill, approved by the state legislature, would have eliminated all penalties for possession of up to one ounce of cannabis and possession of up to six marijuana plants. It would not have allowed marijuana sales, but it would have created a commission to study how to legalize, tax, and regulate marijuana sales — potentially as soon as 2018.

Scott, however, didn’t approve. He sent the bill back to the legislature recommending amendments that would impose tougher penalties for selling or giving cannabis to minors, more aggressive penalties for driving under the influence or using pot in front of minors, and more stakeholders represented in the new commission.

“We must get this right,” Scott said. “I think we need to move a little bit slower.”

In 2012, Colorado and Washington state became the first two to legally allow pot for recreational purposes. Since then, six other states, from Massachusetts to California, and Washington, DC, have legalized marijuana — although DC, like Vermont’s bill and unlike the other states to legalize so far, does not allow recreational pot sales.

Vermont would have become the first state to legalize marijuana through the legislature instead of a ballot initiative.

Supporters of legalization argue that it eliminates the harms of marijuana prohibition: the hundreds of thousands of arrests around the US, the racial disparities behind those arrests, and the billions of dollars that flow from the black market for illicit marijuana to drug cartels that then use the money for violent operations around the world. All of this, legalization advocates say, will outweigh any of the potential downsides — such as increased cannabis use — that might come with legalization.

Opponents, meanwhile, claim that legalization will enable a huge marijuana industry that will market the drug irresponsibly. They point to America’s experiences with the alcohol and tobacco industries in particular, which have built their financial empires in large part on some of the heaviest consumers of their products. This could lead to far more people using pot, even if it leads to negative health consequences.

On Wednesday, the opponents won in Vermont.

For more on the debate over marijuana legalization, read Vox’s explainer.

Correction: This article originally said Vermont would become the 10th state to legalize marijuana for recreational purposes. It would become the ninth.