The US Supreme Court ruled that American anti-HIV groups who work in countries around the world are no longer needed to take a pledge against prostitution with the court stating that it was a violation of free speech.
Global health advocates said the decision lifts the stigma of dealing with sex workers and their role in the world's three-decade-long HIV epidemic, and will allow scientists to talk more openly about approaches that work.
"We know that stigma plays a huge role in driving the global AIDS epidemic and this was a very stigmatizing law against a population that is one of the most vulnerable in the epidemic," said Chris Collins, director of public policy at amfAR, the Foundation for AIDS Research.
In 2003 programs that received US funds under the President's Emergency Plan for AIDS Relief (PEPFAR), a global program devised by former president George W. Bush, were required to make an anti-prostitution pledge in order to receive funds.
On Thursday, the US high court found in favor of public health groups who challenged the condition. Chief Justice John Roberts said it went against First Amendment protections because it required groups "to pledge allegiance to the government's policy of eradicating prostitution."
A second restriction added by Congress remains, stating that no PEPFAR funds can "be used to promote or advocate the legalization or practice of prostitution or sex trafficking."
Population Action International president Suzanne Ehlers said that the program's anti-prostitution pledge was a "harmful policy" that had damaged anti-AIDS efforts around the world.
"Our colleague organizations have documented numerous examples of the pledge's harmful effects, such as a condom shortage among sex workers in Mali, the withholding of safe sex information from young male sex workers in Cambodia, and the closure of community-based health centers in Bangladesh," she said.
"Evidence, not ideology, should drive policy governing public health programs."
According to Melissa Hope Ditmore, the editor of the Encyclopedia of Prostitution and Sex Work, the policy had a range of effects on US groups working in Africa and Asia that wanted to help sex workers as part of their strategy to end HIV transmission.
"Some closed, some hid them, some didn't publicize things that were effective and others turned down the money," she told AFP, calling the court ruling a "great improvement" for organizations on the ground.
"They will now be able to talk about good programming they have done with sex workers. They will be able to talk about evidence-based programming, instead of ideologically based programming, which is what this promoted."
PEPFAR initially committed $15 billion over five years aimed specifically at providing anti-retroviral drugs to people infected with HIV, and is widely hailed as a pioneering US achievement in fighting the global AIDS epidemic.
Its current budget is about $5.5 billion annually.
The press office of PEPFAR did not immediately respond to an AFP request for comment on the decision.
But health advocates were hopeful that the changes would reach those most in need.
"I think this will have practical impact. I think it will mean groups are able to be more open about serving this high-risk population," said Collins.
"Groups addressing the AIDS epidemic will feel more secure in being open about getting appropriate services to sex workers and that is an absolutely critical thing we need to do."