Colorado, Washington approve recreational marijuana use Voters in Colorado and Washington on Tuesday approved measures allowing adults to use marijuana for any purpose, NBC News projected, marking an historic turning point in the slow-growing acceptance of marijuana usage. In Massachusetts, voters also approved an initiative allowing people to use marijuana for medicinal purposes, NBC News projected. In Arkansas, a similar initiative failed, according to NBC News projections. In all, voters in six states were being asked to decide on a wide array of laws around legalizing marijuana for medicinal or recreational purposes. In Oregon, NBC News projected that the initiative to legalize marijuana had failed. In Montana, NBC News projected that voters had approved a plan to to revamp an existing medicinal marijuana law to make it more restrictive. Late Tuesday, a spokesman said in an e-mail that they were reviewing the Colorado initiative and had no immediate comment. Opponent Kevin Sabet, a former senior advisor to the Obama administration and an assistant professor at the University of Florida's college of medicine, said he was expecting legal challenges at the state and federal level. "This is just the beginning of the legalization conversation, so my advice to people who want to toke up legally or think that they can buy marijuana at a store tomorrow is that we're a very long way from (that)," Sabet said. Proponents of the legislation also said they expected some legal wrangling. "It sets up a clear and obvious challenge with the federal government," said Allen St. Pierre, executive director of NORML, which has fought for years to legalize cannabis. But proponents also were celebrating what they saw as a turning point in a long-running battle to make marijuana more available to the general public. "We are reaching a real tipping point with cannabis law reform," said Steve DeAngelo, a longtime advocate for legalizing marijuana and the director of the nation's largest medical cannbabis dispensary, Harborside Health Center in Oakland, Calif. Colorado Gov. John Hickenlooper acknowledged legal challenges but said the state would work to resolve the conflict between federal and state laws. It's probably going to pass, but it's still illegal on a federal basis. If we can't make it legal here because of federal laws, we certainly want to decriminialize it," he told NBC's Brian Williams. The initiatives in Washington, Oregon and Colorado would take things one step further, explicitly allowing people to smoke pot for more than just medicinal purposes.