Vermont has become the first state in the nation to legalize marijuana legislatively.

Gov. Phil Scott signed a bill Monday legalizing marijuana for adults over 21. It allows for the possession of an ounce or less of marijuana, two mature and four immature plants. Vermont is the ninth state to legalize recreational marijuana for adults. The other states did so through ballot initiatives.

But Vermont's law is notable for what it does not do: create a state marketplace for the sale of marijuana.

Instead, it directs a marijuana advisory board to study what a legal marketplace where marijuana is taxed and regulated would look like in Vermont and report to the governor by Dec. 15. Scott was concerned about sales in the state and what he considered weak penalties for selling the drug to minors.

"Today, with mixed emotions, I have signed H. 511," Scott said in a statement. "I personally believe that what adults do behind closed doors and on private property is their choice, so long as it does not negatively impact the health and safety of others, especially children."

The measure creates a number of new marijuana laws, including stronger penalties for selling marijuana to people under 21 or enabling their consumption of the drug and makes it a crime to use marijuana in a vehicle where there is a child. It also makes the consumption of marijuana in public illegal.

Scott said the commission must create education campaigns around marijuana and ways to keep the state's roads safe.

"To be very direct: There must be comprehensive and convincing plans completed in these areas before I will begin to consider the wisdom of implementing a commercial 'tax and regulate' system for an adult marijuana market," Scott wrote.

The law will take effect in July.

"We applaud lawmakers for heeding the calls of their constituents and taking this important step toward treating marijuana more like alcohol," said Matt Simon, New England political director for the Marijuana Policy Project.