More than a hundred scientists from America's top universities have warned that the pro-gun lobby is hampering the search for a solution to firearms violence, in an open letter.

Letter from scientists on gun research

An eminent group of experts, from economists and doctors to criminologists and health researchers, have signed an open letter to vice president Joe Biden, calling for more freedom to study issues of gun violence.

The letter was organised by the Crime Lab research centre at the University of Chicago, as part of the national debate on firearms in the wake of December's school massacre in Newtown, Connecticut.

Mr Biden is considering a range of policy proposals, and said he would be handing over his recommendations to President Obama by next Tuesday. Among the groups he has been meeting at the White House is the National Rifle Association, a powerful lobby for gun rights.

But in their submission, the scientists have accused the NRA of helping to restrict research into the whole issue - saying that a national commission had found that very little was known about effective ways to tackle such violence.

Funds restricted

Despite the fact that firearms account for so many deaths in the United States, says the letter, the Centres for Disease Control (CDC) and the National Institute for Health (NIH) are expressly forbidden from using funds to "advocate or promote gun control". That, they say, has included scientific studies.

After intensive lobbying by the NRA, Congress imposed budget limits on research into gun violence by the CDC and its funding for such studies has fallen sharply since the mid 90s. Between 1992-96, that level was around $2.5m a year: by 2009-12 it had slumped to just $100,000 a year.

In 2009, an NIH study which investigated the link between carrying a gun and the risk of being shot in an assault found that risk was almost 4.5 times higher.

Two years later its funding was similarly restricted by legislation.

Michael Halpern from the Union of Concerned Scientists also claims that pro-gun lobbying meant that Obama's health care law contains provisions which restrict doctors and health insurers from collecting data about patients' gun use, and using it for research.

In Florida, legislation passed last year threatened to punish doctors if they even asked patients whether they owned a gun - although the law was subsequently overturned by a federal judge.

In 2011, as Reuters points out, the NRA attacked what it described as "junk science studies", which it said were "designed to provide ammunition for the gun control lobby by advancing the false notion that legal gun ownership is a danger to the public health instead of an inalienable right."

NRA spokesman Andrew Arulanandam told CNN this week: "If gun control groups...(and) individuals want to further their research, we're not saying they shouldn't do it. We're just saying they shouldn't be using public funds to do it."

However the experts behind the open letter have called for more funding to be given to federal agencies to conduct unbiased research into developing and evaluating policies aimed at reducing gun violence, as well as collecting comprehensive data.

According to Halpern, without rigorous research, the more intractable the debate will become. "One critical step the task force should embrace is to lift restrictrictions on the research public health scientists can do", he said. "And we can all reject attempts to discredit evidence that challenges our beliefs."

Felicity Spector writes about US affairs for Channel 4 News