Now Nevada plans to step it up a notch by being the first state to openly allow businesses to host public marijuana use.
States with medical marijuana laws also saw an increase in people who can't stop using pot even though it's interfering with many aspects of their lives, researchers said.
He cited "a growing body of research" suggesting marijuana's chemicals can help with 'pain, nausea, epilepsy, obesity, wasting disease, addiction, autoimmune disorders, and other conditions'.
Be aware that cannabis usage may be more socially acceptable in states with medical marijuana laws, leading to an increase in reporting in the absence of a true increase of illicit use.
They used data from national surveys of drug use among adults (ages ≥18) conducted at three time points: before the enactment of medical marijuana laws (1991-1992); just after the laws were enacted in a few states (2001-2002); and after wide enactment of the laws (2012-2013), when more than one-third of people in the US lived in states with MMLs.
Pacula added that people should be cautious in interpreting the new study, because it uses national survey data to evaluate state-level trends.
From 2001 to 2013, illicit use increased 3.5 percentage points in states that had not legalized medical marijuana. By comparison, in states where the drug did become legal for medical use, the rate of illicit use went from 5.55 percent to 9.15 percent.
Hasin and her colleagues estimate that medical marijuana laws have led to an additional 1.1 million adults illicitly using pot and 500,000 more adults with a diagnosable cannabis disorder.
Having said that, one of the reasons other states have been wary of taking this step is that the attitude of the federal government has been less than hospitable towards the marijuana industry.
The increase in cannabis use disorders could stem from the increasing potency of pot that has occurred under legalization, Hasin said.
NY recently expanded its medical marijuana program by adding chronic pain, but there is an important group of patients who are still left out - those who suffer from post-traumatic stress disorder (PTSD).
According to the NDAA Perspective, "As a Schedule I drug, federal authorities have found that marijuana has a high potential for abuse, no accepted medical use, and lacks safety for use under medical supervision".
However, medical marijuana laws may be driving up the use and abuse of the drug among adults.
But the authors of the study also note several limitations.
Dr. Wilson Compton, the deputy director of the National Institute on Drug Abuse, said the recent research was a "strong design to test the implications" of the new marijuana laws.
Compton compared these laws to laws that regulate alcohol in the states.
For more on state medical marijuana laws, visit the U.S.