Answer:
No, they would not have been able to legalize recreational marihuana.
Step-by-step explanation:
This is because, in an unitary system, administrative divisions like Georgia or Colorado have very few powers, and certainly, they do not have any legislative powers.
All legislation emerges from the central government in an unitary system, and this means that if the U.S. was an unitary system, the law to legalize recreational marihuana would have to come, exclusively, from the U.S. Congress.
Unless the U.S. Congress legalized marihuana nationwide, no state would be allowed to do so under an unitary system. it would continue to be prohibited.