Rod Rosenstein needs to visit San Francisco.

The country’s deputy attorney general should stroll the sidewalks around City Hall, the Tenderloin and South of Market. He should count the dirty needles strewn at his feet as he two-steps carefully around them. He should observe the drug users jabbing needles into their necks and thighs and between their toes in broad daylight as city officials and police officers look the other way.

He should learn some statistics. That there are 22,500 injection drug users living in San Francisco. That the city last year oversaw the distribution of 4.5 million free syringes and is on track to hand out 6 million this year.

Then he’d know that San Francisco already sanctions injection sites. It’s just that these sites are our sidewalks, BART trains and stations, Starbucks restrooms and playground sandboxes. Then he’d see why it would be far, far better to move that stomach-churning public drug use and those dangerous dirty needles inside to a supervised, sterile location where the rest of us wouldn’t be confronted with it.

In an opinion piece in the New York Times on Monday, Rosenstein said it is unfortunate that some cities — San Francisco included — are contemplating opening safe injection sites where drug users “can abuse dangerous illegal drugs with government help” and “without fear of arrest.” Like I said, San Francisco already offers exactly that.

He said that because opening these sites would violate federal law, any city that does so should expect “swift and aggressive action.” That could include up to 20 years in prison, big fines and the forfeiture of property for anybody running one of these sites, he continued.

And then what? All the drug users go back outside and keep using while the compassionate nonprofit workers and city officials who tried to help them sit in jail and the nonprofits that offered the space go broke? That makes no sense.

It could be argued that the alternative is cracking down on public drug users now, with or without a safe injection site. But under California law, the personal use of most illegal drugs is a misdemeanor. And I don’t think most San Franciscans want our jails filled with drug users anyway.

Rosenstein should have visited San Francisco last week, as the city opened a model of a safe injection site — minus the drug users and heroin — in Glide Memorial Church’s aptly named Freedom Hall. I toured the site and, rest assured, it was immeasurably cleaner, safer and more welcoming than our sidewalks. It had all the grit and menace of a doctor’s office in the suburbs.

Yes, it was a little weird at first to see the smiling staffer sitting beside a cart stocked with free drug paraphernalia, including syringes, cotton balls, tourniquets and “cookers,” little metal caps used to heat and mix water and powdered drugs so they’re injectable.

Yes, it was a little weird to envision drug users sitting at one of the stainless steel tables with a mirror so they can be sure to target the correct vein and staffers can see if they appear to be overdosing. Yes, it was a little weird to picture people high on drugs then ambling over to the “chill out” room where they can gaze at artwork on the walls or play board games.

But no, the city won’t fund or distribute the drugs. And no, staffers won’t help users inject. And no, minors under 18 won’t be allowed. It’s just a safer way of allowing the behavior the city already allows.

In a perfect world, we wouldn’t need these facilities. But we’re not in a perfect world, we’re in drug-addled San Francisco.

The benefits of these sites are obvious. San Francisco had 193 overdose deaths last year, according to Mayor London Breed. There has never been an overdose death at any of the safe injection sites in Canada, Europe and Australia.

Research shows the sites help prevent the spread of HIV and hepatitis C, and reduce the number of dirty needles on the streets — and there are a lot of dirty needles on San Francisco streets. The sites also link drug users to treatment programs if they are interested. The mayor says opening one site would save the city $3.5 million a year in ambulance rides and treatment for diseases and overdoses.

Breed, whose sister died of a drug overdose, really wants to open the nation’s first safe injection center. The Department of Public Health pledged this year that two would open by July, but the City Attorney’s Office warned the legal ramifications would be huge.

Breed got some cover Monday when the state Legislature approved a bill allowing San Francisco to operate a pilot program for safe injection sites for four years. That means the city wouldn’t be violating state law, but it doesn’t erase the federal liability. Gov. Jerry Brown is notoriously unpredictable, but most insiders expect him to sign the bill.

So now what? Breed said she will “open one as soon as possible,” but gave no timeline. She said she’s looking at “creative solutions,” including turning the safe injection sites into research facilities where scientists would study the effects of opioid use. It’s unclear whether that would help ease the concerns of the federal government.

She also said there is “strength in numbers” and alluded to all the cities considering opening safe injection sites — they include Seattle, Philadelphia and New York — opening them all at once as a show of force against the Trump administration. (Note to mayors: If you do this, wait until after the midterm elections. Please.)

Asked whether Glide would brave opening a safe injection center for real, and not just a model, co-founder Janice Mirikitani said: “We would be honored. ... We’ve been known to take risks knowing it’s the right thing to do to save lives, to provide an environment where people can receive treatment and counseling.”

She emphasized she was speaking for herself and has not talked about the idea with Glide’s CEO or board of directors.

Others, too, are willing to take the leap. I asked several people staffing the model safe injection site if they’d be willing to face arrest to work in a real safe injection site. They all said yes.

One of those was Paul Harkin, Glide’s harm reduction program manager. He said people already shoot up in Glide’s restrooms, in the restrooms of nearby businesses and on the sidewalks outside. Most of them, he said, don’t even get a pleasurable high anymore. They’re just shooting up to avoid feeling sick.

“I would be gladly arrested for trying to move people along the continuum of health care,” he said.

He figures the city needs to open four safe injection sites in the blocks around Glide, keep them open for most of the day and night, and have space for 10 drug users at a time in each one.

Would that make a difference on our streets?

“Absolutely,” he said. “What we’re doing doesn’t work. Just look around your streets. There’s zero downside.”

It took just a minute after I left the model site at Glide to find a man on Jones Street hunched over a suitcase on which needles and other drug paraphernalia were spread. He mumbled pretty incoherently, but I did catch that his name is Nicholas, he’s 32 and he’s been using heroin since breaking his back years ago.

Most of his teeth were missing, his nails were dirty and long like talons, and his clothes were filthy and covered in red splotches that might have been blood. I asked if he’d inject inside a safe facility with free needles if it was allowed.

“I would totally do that — hell yeah!” he said.

If Rosenstein would walk San Francisco’s streets and meet people like Nicholas, I wonder whether he would still think that young man is better off just where he is than inside under supervision. And whether the rest of the city’s residents are better off walking around him and his needles, pretending he’s not there.

San Francisco Chronicle columnist Heather Knight appears Sundays and Tuesdays. Email: hknight@sfchronicle.com Twitter: @hknightsf