A little-known kibosh on government research into the public health effects of gun violence is expected to be lifted after President Barack Obama called Wednesday for renewed scientific inquiry -- and funding -- to address the problem.

Obama issued a presidential memorandum directing the Centers for Disease Control and Prevention and other scientific agencies to research the causes and prevention of gun violence -- and he called on Congress to provide $10 million to pay for it.

"We don't benefit from ignorance. We don't benefit from not knowing the science from this epidemic of violence," he said.

The move effectively reverses 17 years of what scientists say has been a virtual ban on basic federal research and is part of a package of new gun control policies aimed at reducing gun violence after tragedies such as the shootings last year in Aurora, Colo., and Newtown, Conn. It would encourage research including links between video games, media images and violence.

The action immediately was praised by scientists who said pro-gun advocates -- including the National Rifle Association -- had choked off funding for CDC firearms research starting in the mid-1990s and imposed a chilling effect on those who dared to pursue it.

"He's saying this is very important and I'm going to back you on this," said Dr. Mark Rosenberg, president of the Task Force for Global Health and director of the CDC's Center for Injury Prevention and Control from 1994 to 1999. "Basically, they've been terrorized by the NRA."

From the mid- 1980s to the mid-1990s, the CDC conducted original, peer-reviewed research into gun violence, including questions such as whether people who had guns in their homes gained protection from the weapons. (The answer, researchers found, was no. Homes with guns had a nearly three times greater risk of homicide and a nearly five times greater risk of suicide than those without, according to a 1993 study in the New England Journal of Medicine.)

But in 1996, the NRA, with the help of Congressional leaders, moved to suppress such information and to block future federal research into gun violence, Rosenberg said.

An amendment to an appropriations bill cut $2.6 million from the CDC’s budget, exactly the amount the agency’s injury prevention center had previously spent on gun research. The money was returned to the agency later, but targeted for brain injury trauma research instead.

In addition, the statute that governs CDC funding stipulated that none of the funds made available to the agency can be used in whole or in part “to advocate or promote gun control.”

While that did not specifically prohibit firearms research, the language was ambiguous enough to alarm CDC officials and stifle scientists interested in gun data, said Stephen Teret, director for the Center for Law and the Public’s Health at the Johns Hopkins Bloomberg School of Public Health.

“CDC overreacted to that statement and became more reluctant to fund anything dealing with guns, even the traditional epidemiological research, so there was a chilling effect,” Teret said.

The NRA attacked some scientists, trying to discredit their research, endangering their jobs and even threatening their families, Rosenberg claimed.

“These were not mild campaigns,” he said. “When the NRA comes after you, they come after you with both barrels.”

Officials with the NRA did not return NBC News requests for comment.

The dearth of basic data means that policymakers and the public know little about the causes of gun violence that kills about 32,000 people in the U.S. each year. At the same time, Teret said, research into other public health problems such as automobile deaths has yielded dramatic results.

“When I first started, there were 50,000 people a year dying on the highways. Now it’s 32,000 and that’s because there’s been superb scientific research,” Teret said. “We need to be able to address gun-related injuries in the same scientific manner as highway injuries.”

Obama’s directive will immediately impact federal agencies that engage in scientific research about gun violence, said Health and Human Services Secretary Kathleen Sebelius.

"We are committed to re-engaging gun violence research at the Centers for Disease Control and Prevention and the National Institutes of Health," she said in a statement.

The move may restore the will to research gun violence, but it will be up to Congress to supply the funding to carry it out, the scientists noted.

If that happens, there are talented researchers poised to pursue the projects, said Dr. Frederick Rivara, a pediatrician and editor of the Archives of Pediatrics and Adolescent Medicine.

He estimated that if CDC were given the green light for research now, scientists could have meaningful results that could be used to shape public policy within a year or two.

“We’ve lost almost 20 years of really waiting around,” said Rivara. “Given how large a public health problem this is, it’s a tragedy.”

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