"Good people don't smoke marijuana."

U.S. Sen. Jeff Sessions, R-Alabama, said that at an April 2016 Senate hearing on enforcement of marijuana laws. Sessions is now Republican president-elect Donald Trump's nominee to become attorney general, the United States' highest law enforcement officer and the one in charge of overseeing implementation of federal marijuana laws.

Massachusetts, through a ballot initiative, just became one of the eight states to legalize recreational marijuana. Sessions' nomination raises questions about whether the federal government might crack down on marijuana use or sales, even in states that have legalized it, and what that could mean for Massachusetts.

"There's no way to sugarcoat it," said Adam Fine, a Boston attorney with Vicente Sederberg, a law firm that specializes in marijuana policy and represents the marijuana industry. "The reality is he's probably one of the worst picks for the marijuana industry."

There are numerous questions swirling around the Trump administration's marijuana policy, ranging from their political will to enforce federal marijuana law to the practicality of doing so.

Sessions is a strong opponent of legalization, arguing that marijuana is dangerous and legalization encourages its use. He has supported strong penalties for drug crimes.

But Trump said during his campaign that he would leave marijuana laws up to the states. He has supported medical marijuana.

"I think it's too early to tell what the administration's tone is going to be," said Matt Simon, New England political director and legislative counsel for the Marijuana Policy Project, a pro-marijuana advocacy group.

Legally, marijuana is illegal under federal law. So if the U.S. Drug Enforcement Administration chooses to enforce that law, it can.

"If the DEA wanted to arrest someone for a joint, they could do it," Simon said. "They could prosecute someone in federal court. That's not been the practice."

Traditionally, almost all arrests for marijuana possession and sales have been made by state law enforcement, with the federal government stepping in mostly to prosecute large-scale drug trafficking.

Under current Democratic President Barack Obama's administration, the federal government has made clear that it will not prosecute marijuana offenses when someone is complying with state law. That has given free reign to four states to allow legal marijuana industries, with retail stores selling marijuana and state governments taxing and regulating the products. Four more states voted to legalize recreational marijuana this year. Nearly 30 states allow medical marijuana.

Fine said he anticipates that medical marijuana will remain untouched. In addition to the prevalence and popularity of medical marijuana in both Republican and Democratic states, an amendment that Congress tacked onto spending bills each of the last two years prohibits the Department of Justice from interfering with state medical marijuana programs.

"The question mark really sits with recreational marijuana," Fine said.

Legal experts and advocates on both sides say if the U.S. government decides to crack down on states that legalized marijuana, they are unlikely to arrest individual users, since that would take a huge amount of resources to catch lots of small-time users. The more effective and efficient way would be to target retail sales and commercial growers.

The U.S. Drug Enforcement Administration could raid individual stores or growing facilities. It could also demand that marijuana operations cease, with a threat of enforcement if the order is not followed. Either of those steps would effectively freeze the marijuana business.

"They could certainly create problems for the regulated market system," Simon said.

In Massachusetts, no matter what federal officials do, state officials would still be bound by state law to create a regulatory structure for legal marijuana -- including an oversight commission, detailed regulations and a licensing process for marijuana shops. But if the federal government intercedes, there may not be an industry to regulate.

Massachusetts Senate President Stan Rosenberg, D-Amherst, and House Speaker Robert DeLeo, D-Winthrop, both said Sessions' appointment would not affect their commitment to working to implement the state law as passed by voters.

The Trump administration could also issue a legal order arguing that state marijuana laws are pre-empted by federal law -- a question Fine said would probably end up being decided by the courts. But even if that is successful, the federal government cannot force states to make marijuana possession or sale a state crime -- it can only outlaw the tax and regulatory schemes that make marijuana commercially available.

Advocates for marijuana legalization warn that in addition to eliminating jobs that already exist in the marijuana industry, federal enforcement would force the marijuana market back underground. "We're talking about over a $1 billion market in Colorado alone that would shifted back into an unregulated illicit market," Simon said.

The DEA cannot require state and local law enforcement to enforce federal marijuana law. But local police can cooperate with federal authorities if they want to.

Norwood Police Chief William Brooks, president of the Massachusetts Chiefs of Police Association, which opposed legalization, said he thinks the attitudes of local law enforcement will depend on the way the federal government implements its policy. If the U.S. government makes a change gradually -- issuing an order requiring that sales be stopped by a certain date, to give the industry time to respond, Brooks said he thinks some local law enforcement would be open to collecting evidence and handing it over to federal authorities for prosecution, if someone ignored the federal law.

"I think most police were opposed to this in the first place," Brooks said. "I think police departments would have an interest in curtailing that as long as we understood this is what the federal government wanted to do."

Brooks said he thinks the U.S. government can legitimately argue that retail sales in a state like Massachusetts will impact bordering states, as has already happened with legal marijuana from Colorado flowing into surrounding states. "The federal government has a role to play," Brooks said. "It will be interesting to see if they take a step in that direction and how they go about it."

The Massachusetts State Police did not respond to a request for comment. State Attorney General Maura Healey's office also declined to comment.

Bill Downing, member liaison for MassCann/NORML, the Massachusetts chapter of a pro-marijuana legalization advocacy group, said he believes enforcing federal marijuana law in states like Massachusetts would be a "terrible mistake" politically.

"I think it would be extremely unpopular, " Downing said. "The states have been allowed to conduct this experiment, and the citizens of the states have made their opinions clear through the ballot box."

Downing said the spread of marijuana legalization nationally is "like a giant freight train rolling down the track very quickly" that will eventually influence federal policy. Recent national polling by Gallup and the Pew Research Center has shown around 60 percent of Americans support marijuana legalization.

Downing said using federal resources to enforce what has been state law would be expensive and could galvanize pro-marijuana activists. "If you want people out screaming in the streets and protesting and using their civil rights to express their dismay, then bring it on," Downing said.