In an essay published yesterday for World AIDS Day, the director of the Centers for Disease Control painted a bleak picture of the United States’ effort to fight the epidemic. Although medical advances have turned a positive HIV diagnosis from a death sentence into a survivable condition, there are more than 45,000 new cases of infection every year, and 156,000 of the 1.2 million Americans living with HIV are undiagnosed. CDC director Thomas Frieden called on public-health officials to increase their efforts in ending the disease, including notifying partners of people who test positive.

But neither the CDC nor the White House called for what many activists say is the most important measure to stop AIDS: ending laws that criminalize people with HIV.

Thirty-three states have at least one law that specifically criminalizes behavior for an HIV-positive person that would otherwise be legal, according to the Centers for Disease Control. Most of these laws focus on disclosure of HIV status prior to sexual contact, but 25 states also criminalize behaviors “that pose a low or negligible risk for HIV transmission.” According to Sean Strub, executive director of Sero Project, a network that combats HIV stigma, that can mean “spitting, biting, scratching, or other behaviors that don’t transmit HIV.” Since a person has to know their status to be held criminally liable, Strub says the laws have the perverse effect of encouraging ignorance. “The threat of prosecution is stigmatizing, makes people less willing to get tested (‘take the test and risk arrest’), [and] penalize[s] the responsible behavior of knowing your HIV status while privileging the ignorance of not knowing it,” he said in an e-mail.

Many of these laws were passed in the 1980s and 1990s, when public fear of HIV and AIDS was at its height, and are closely linked to homophobia and fear of drug users. In some cases, the sentences handed down for violating the HIV laws can lead to decades behind bars. A Missouri jury sentenced former college wrestler Michael Johnson to 30 years in prison after finding him guilty of transmitting HIV to one man and exposing or attempting to expose four others. Proponents of the laws argue they serve as a deterrent to HIV-positive people seeking to actively spread the disease. “I think I speak for most prosecutors in stating that in certain circumstances, there certainly should be a criminal statute where people should be punished for knowingly, intentionally infecting someone with the HIV virus,” Scott Burns, executive director of the National District Attorneys Association, told CNN in 2012.

In practice, activists say, that’s rarely how the statutes are applied. “In Sero’s research, we’ve identified more than 1,000 instances when charges were filed under HIV specific statutes, yet HIV transmission was a factor in only a very small percentage (significantly less than 10% of the cases),” Strub said.

Whatever the original intent of these laws, critics say they are based on outdated assumptions about HIV and AIDS. “It’s living with knowledge of HIV from the 1980s,” said Amira Hasenbush of the Williams Institute, a think tank dedicated to studying sexual-orientation and gender-identity law. According to a 2013 study, life expectancy for people in their 20s who contract HIV is nearly the same as the general population on average, and a once-onerous medication cocktail can, in many cases, be simplified to taking a single pill once a day. Not only do the laws not take into account available treatment options, critics say, but they also fail to recognize that according to two large studies from the last five years, transmission rates among patients with low or undetectable viral loads were very small.

Hasenbush is the co-author of a report released yesterday that examines HIV criminalization laws in California. Beyond individual harsh sentences, the Williams Institute findings suggest the impact of HIV-criminalization laws is much broader than previously known. The study found that 800 people came into contact with the California criminal-justice system under HIV-specific state laws since 1998. Some earlier estimates had put the total number of people arrested under these laws at slightly over 1,000 nationwide.

Nearly all of the arrests in California—95 percent—involved sex work. “So that means people have been arrested, tested HIV positive, and then arrested a second time,” Hasenbush said in a phone interview. “The law doesn’t require any sexual contact, and has nothing to do with intent.” And not all suspected sex workers are prosecuted equally. The study found that white men were allowed to walk away without charge 70 percent of the time, while only 42 percent people of color and white women escaped without a charge.

Even in states without HIV-specific laws, state and city policies can criminalize HIV prevention. In New York, for instance, carrying clean needles is illegal unless you’re enrolled in a state-sponsored program like a needle exchange. But a 2013 study of syringe-access programs in New York by HIV/AIDS advocacy group VOCAL NY found that 90 percent of the people who reported being arrested for syringe possession had a card showing they were enrolled in a syringe program. According to the CDC, 60 percent of injection-drug users report sharing needles, making access to clean syringes legal and safe all the more important in combating the spread of HIV.

“The criminal statute on syringe possession is totally counterproductive and should be repealed,” says Matt Curtis, policy director at VOCAL NY. “Legislation was introduced this year but blocked in the Senate and not supported by Governor Cuomo. There’s no legitimate argument anyone can voice for maintaining it.”

For Strub, of Sero Project, the core issue is about civil rights and dignity. “Most people don’t think its a great idea to create a different criminal law for one segment of society based on an immutable characteristic, like race, gender, sexual orientation, physical ability, genetic makeup,” he said. “But that’s what we’re doing with HIV criminalization—creating a viral underclass.”