So far, marijuana is considered a drug as risky as heroine under US Federal Law. In legalization states like Colorado, for example, Sessions essentially decreed that citizens may well need to worry that the massive arm of the federal government could come crashing down on them; their local laws be damned.
That statement includes rescission of the Cole Memo, issued in 2013 and long regarded as providing a safe haven by cannabis entrepreneurs.
James Dunn covers technology, biotech, law, the food industry, and banking and finance. On the campaign trail, Trump often said he thought medical marijuana wasn't that bad and the issue should be left up to the states and voters.
Marijuana remains illegal under federal law, but eight states including California and Colorado have legalized the drug, as has Washington, D.C. Twenty-eight states permit some form of medical marijuana use.
While you probably don't have to worry about getting swept up in a raid by the Drug Enforcement Administration on your way home from the pot shop, according to state officials and pot attorneys, that doesn't mean you can start cutting corners with your basement grow, business plans and pot purchases. They had closed down several hundred before Congress intervened with budget restrictions that halted the lawsuits - one of them targeting Harborside Health Center in Oakland, the nation's largest licensed cannabis dispensary - as well as most federal criminal prosecutions.
There has been a surge in legalization of marijuana at the state level in recent years.
The Sessions memo did not distinguish between enforcement against marijuana used for recreational versus medicinal purposes.More news: Largest known prime number discovered
And Colorado's US attorney, Bob Troyer, who was appointed to his office by Sessions in November, said Thursday that the attorney general's directive would not change his policy to prosecute only marijuana operations that "create the greatest safety threats to our communities".
But rescinding the Obama policy could have a chilling effect on the burgeoning marijuana legalization movement.
Rosenblum, who characterized Sessions' decision as overreach, made no indication of specific next steps other than she "valued her working relationship" with Williams and looked forward to working with him.
Q: Can congress reverse Sessions' action - and would lawmakers be inclined to do so? New Jersey's Governor Elect Phil Murphy has pledged to sign legislation legalizing adult recreational use within 100 days of his new term. White House spokeswoman Sarah Sanders said President Donald Trump's top priority was enforcing federal law "whether it's marijuana or immigration".
Democratic Congresswoman Dina Titus wishes to see legal marijuana continue to flourish.
But many states, including North Dakota and Minnesota, have passed laws decriminalizing the drug for medical reasons.
Arcview Group, an Oakland investment and market research firm that studies the cannabis industry, forecast an $11 billion USA market for legal marijuana this year - just over 60 percent for medical use, the rest for recreational use - and said it would continue to expand. Now he's breaking that promise so Jeff Sessions can pursue his extremist anti-marijuana crusade. How heavily the federal government has to be involved to stop interstate commerce in marijuana is a practical legislative judgment about which the courts have no special expertise or authority.
Sessions' new memo does not explicitly set forth how prosecutors should treat medical marijuana, though a senior Justice official explained that prosecutors wouldn't do anything contrary to any current federal law.