With a couple of old desks, a beat-up couch and an off-white white board, the office space at 149 Turk Street, in this city’s seedy Tenderloin district, is hardly remarkable. A collection of worn detective novels sits on the bookshelf, a couple of American flags hang limply from the wall and a coffee machine constantly percolates in the back kitchen.

It is the tenants who set 149 Turk apart: a ragtag group of current and former drug users who make no apologies about their fondness for illegal narcotics, intravenous experiences and the undeniable rush of getting high.

“If you pass a drug test,” joked Gary West, a member, “you’re outta here.”

But the group, the San Francisco Drug Users’ Union, has more on its mind than simply turning on, tuning in and dropping out. The union is one of several groups in the United States and Canada that advocate for the rights of drug users, following the lead of older European drug user organizations. Their goals are often varied, but carry a common refrain: to represent the political interests — and practical needs — of chronic drug abusers, a sometimes grim agenda that includes everything from providing clean needles to finding safe places to nod out.

It is a job, members say, that requires firsthand experience to connect with a population that is often wary of law enforcement and social service agencies.

“People don’t trust them,” said Isaac Jackson, who helped found the group and is, with Mr. West, one of two so-called peer organizers. “So someone being a drug user here is somewhat desirable, because who knows best about drugs than those that use them?”

The group says they are not promoting illegal drug use, just confronting the reality that many people use. Still, such openness can make their work difficult, as can their name, Mr. Jackson said.

“People think it’s a joke,” he said. “They think of union as a kind of trade union. They don’t understand that we’re using ‘union’ in the sense of a consumer union. And we’re consumers of drug policies, we’re consumers of rehab, we’re consumers of drugs.”

Yet with attitudes about drugs and the drug war seemingly evolving in many areas — including ballot measures this fall to legalize marijuana in Washington State and Colorado — drug advocacy groups have had some recent successes. In New York, the group Voices of Community Activists and Leaders (or Vocal), a membership group of people with AIDS, drug users and former prisoners, has helped pass a pair of bills involving syringe access and protections for users who call in overdoses to 911.

In San Francisco, the drug union received its first grant in 2009, Mr. Jackson said, and got more help in December 2010 from the city’s Hepatitis C Task Force, which advocated for a pilot “supervised injection facility” for intravenous drug users because they often contract hepatitis by using dirty needles. No such facility exists in the United States — a so-called safe injection site in Vancouver, British Columbia, has been considered a success there — and it has become a central goal of the San Francisco union.

Advocates for such a site say it would not only help prevent new hepatitis and AIDS infections but could also provide a contact point for other health services, including rehabilitation, for addicts who are often loath to seek help.

And in one of the more liberal cities in the nation, the idea of a safe injection site has won some support, including from several mayoral candidates last fall like John Avalos, a leader of the progressive bloc of the city’s all-Democratic Board of Supervisors. Laura Thomas, the interim California director for the Drug Policy Alliance, a drug reform organization in New York that helps finance the union, said that San Francisco had a history of “compassionate response” to drug users, and that an injection site was not so far-fetched.

“I have a small bet with one of my co-workers as to who is going to get there first, New York or San Francisco,” Ms. Thomas said. “Certainly I want San Francisco to be the first.”

Still, such a plan faces political and economic challenges, said Alice Gleghorn, the county alcohol and drug administrator, who oversees the city’s drug abuse prevention and treatment programs and opposes the idea of an injection site. “We do have trouble even in San Francisco finding locations for new substance abuse programs,” Ms. Gleghorn said. “Can you imagine what kind of Nimbyism would come about if someone were to try to put a safe injection site somewhere?”

Mayor Ed Lee also opposes the idea, saying that the city has ample tools for attacking the problem of intravenous drug use, including syringe exchanges, said Christine Falvey, a spokeswoman for the mayor.

Mr. Jackson, 56, admits to using methamphetamine — his drug of choice, one he said was “love at first sight” — despite a personal history that would probably argue against it.

Tall and gangly, with a drifting eye, Mr. Jackson speaks with a mumble and a dry sense of humor about losing most of the perks of a normal life — car, career, apartment — to meth, something he feels might have been avoided had a group like his been around at the time.

“If there was more information out there, I could have known how to stay safe,” Mr. Jackson said.

The group, whose activities never include asking anyone to stop doing drugs, holds regular meetings at the Turk Street space, in an area where drug sales are common. People wander in and out, though Mr. Jackson and Mr. West are constant presences.

Mr. West, 46, says he came to San Francisco two years ago from his home in Ishpeming, Mich., in the state’s Upper Peninsula, and was attracted initially to the union by the promise of free pizza. “It was an inside joke for me at the time,” he said. “My dad would be so proud of me: ‘I’m a drug user, but I finally joined a union!’ ”

But he found himself agreeing with much of what Mr. Jackson was talking about. “And I need something to fill in my time as well,” Mr. West said. “Living on the street you get awful bored.”

He is still homeless — “I have a little camp in a secret locale” — but now draws a small salary from the union, as does Mr. Jackson. It is not much, the men say, but enough to keep them out of soup kitchens.

But both men say their experiences with a range of drugs are indispensible in helping their members.

“It helps to know what they are doing and what they’re going through while they’re high,” Mr. West said. “If they are tweaking, we got to figure out some way of how to tie them down. If they’re doing heroin or something like that, that’s easy, just turn on the TV, and that’ll keep them occupied.”

At a meeting in late February devoted to a discussion of current events, one such member had nodded out in a chair. But still the conversation continued, touching on the presidential campaign — “Ron Paul would be good for us, for druggies,” quipped Mr. Jackson — and plans for an April exhibit at the Turk Street space outlining potential plans for the injection site.

And while those plans may be far from fruition, Mr. Jackson says that he is as committed to it as he is to his belief that drug users are people, too.

“I think people feel that drug users are powerless or are impossible to work with,” he said. “That we can’t get it together. But I don’t think that’s true.”

This article has been revised to reflect the following correction:

Correction: March 11, 2012

An earlier version of this article misspelled the given name of one of the founders of the San Francisco Drug Users’ Union. The cofounder’s name is Isaac Jackson, not Issac Jackson.