U.S. attorneys in Philadelphia and Vermont have come out strongly against supervised injection sites. But Rosenstein’s vow marks the first time a high-ranking Department of Justice official has weighed in on the controversial sites that Philadelphia and about a dozen other jurisdictions are considering as a desperate response to the worsening opioid crisis.

Nonetheless, top city officials said Rosenstein’s declaration will not deter them from forging ahead toward the opening of a facility where people can administer their own drugs under the supervision of medical professionals.

That plan amounts to a flagrant violation of federal drug laws, Rosenstein countered.

“I’m not aware of any valid basis for the argument that you can engage in criminal activity as long as you do it in the presence of someone with a medical license,” he said.

Drug users struggling with opioid addiction in Kensington and other places hard hit by the crisis need treatment, not government-sanctioned places to use a deadly drug, he said.

“You can’t possibly think you’re going to solve the problem … in Kensington by setting up a place where people can actually come in and legally, at least with the sanction of the local government, inject drugs,” Rosenstein said.

His advice to Mayor Jim Kenney and other top elected officials: Consult your lawyers about all legal repercussions.

That could mean criminal prosecution.

“We also have the ability and the Controlled Substances Act to pursue an injunction that is a civil order that a court would impose to order somebody to stop engaging in unlawful activity to stop distributing drugs illegally,” Rosenstein said. “And so both of those tools are available, and … if the situation arose where we determine that somebody was in violation of the law, we’d have to evaluate the facts and make a determination about what’s the appropriate approach to take.”

Rosenstein said he “wouldn’t speculate” on what exactly the enforcement would look like or who might be arrested, but he said federal officials have their eyes trained on Philadelphia.

City leaders, he said, should expect legal action as soon as the city opens a facility.

‘Worth a try’

But Philadelphia city officials, confounded by a staggering death toll, have said a facility where people can inject drugs under supervision is one way of saving lives.

More than 1,200 people died of drug overdoses, most fueled by opioids, last year. That is about 35 percent more than the deadliest days of the AIDS epidemic, said Philadelphia Health Commissioner Dr. Thomas Farley.

“This would be the worst public health crisis in a century,” Farley said.

While he was disappointed with the Department of Justice’s hardline response, Farley mentioned the initial backlash to needle-exchange programs, widely seen as helping to curb the AIDS epidemic, as a hopeful analogy.

“If the message is clear that, if you walk in this facility you’re going to be arrested, people wouldn’t be using that,” Farley said. “But that is not what is happened currently with syringe exchange, and that’s the sort of accommodation we hope we can set up with an overdose prevention site.”

The evidence is clear, Farley said. In countries that have opened supervised injection sites, overdose deaths have dropped.

“Nobody likes the idea of watching someone who is addicted just inject drugs. We want to get all of those people into treatment, but we all have to recognize that, despite all of our efforts, many people are not going to drug treatment.

“In a crisis like this, with as many people dying as we have, it’s worth a try,” he said.

‘All of our problem’

That message was amplified at City Hall Wednesday afternoon, as dozens who support the plan rallied to push leaders to act more quickly.

A mix of harm-reduction advocates and people who use drugs blocked traffic, holding signs stating “We Will Not Rest in Peace.” They chanted “preventable deaths, political crimes,” over a chorus of honking car horns.

Sterling Johnson, an organizer with ACT UP, said he does not think the threat of a federal crackdown should stop the city from taking quick action.

“Just as we’re a sanctuary city, and we’ve seen the mayor make really bold stances — we’re really happy about that — we know that this is another topic that we need to make the same bold stance regarding,” Johnson said

Protester Sandra Collett, a 58-year-old former heroin user, recently lost her partner to a drug overdose. Collett thinks a supervised injection site may have saved her partner’s life. When she was using, she said, it would have provided her with solace knowing medical care and emergency responders were close by.

“They didn’t have safe injection sites when I was using,” Collett said. “We was going in the shooting galleries, and I believe that’s what a lot of people do — go in shooting galleries or old abandoned houses and everything like that where they have a chance of OD’ing all by their self, alone.”

After repeatedly seeing piles of used needles and people openly using opioids near her Kensington bus stop, Collett said she became a supporter of the plan.

“That finally woke me up to say maybe, just maybe, a safe injection site would work. You know? Because this is not just one person’s problem, this is all of our problem,” she said.

The exact timing of Philadelphia supervised injection site has not been announced. It could be a mobile site. It could be housed in a building. Or it could be a portable site in a vacant lot. Officials say, perhaps as soon as the end of the year, there will be another major announcement.

Meanwhile, DOJ officials have other places to watch. California just passed a bill legalizing supervised injection sites in the state. Rosenstein said he was well aware of that.

“Just because somebody tells you in San Francisco that San Francisco is not going to prosecute you for doing something that does not make it legal,” he said. “It remains illegal under federal law. And people who engage in that activity remain vulnerable to civil and criminal enforcement.”

WHYY reporter Nina Feldman contributed to this story