Medical journals are not always the objective, purely scientific publications we might think that they are. Their editors have increasingly strayed into politics at the expense of scientific accuracy. For example, the prestigious New England Journal of Medicine has over the last few months published a number of extremely biased and poorly done studies on gun control.

One of the articles, written by Garen Wintemute, Anthony Braga, and David Kennedy, makes the case for extending background checks to the private transfers of guns, arguing that “perhaps the principal reason for the well-documented failure of the Brady Act to lower rates of firearm-related homicide is that its requirements do not apply to private-party gun sales.” But they do so without providing any evidence that these or any other background checks reduce crime. Further, they conveniently overlook the only research that has been done on what they are proposing. For instance, the updated More Guns, Less Crime specifically studied this very issue and found no evidence that either type of law helped reduced crime.

The only “evidence” that “screening works” comes from their claim that, in 2008, 1.5 percent of those having a Brady background check were denied from purchasing a gun. What the authors likely are aware of, though they do not tell the readers, is that virtually all these cases represent so-called “false-positives”: In 2006 and 2007 (the latest data years available), a tiny fraction — just 2 percent of those 1.5 percent — involved possible unlawful possession; just 0.2 percent of the 1.5 percent were viewed as prosecutable — 174 cases in 2006 and 122 in 2007. At least a third of the remaining cases didn’t result in convictions. These are the types of errors that an academic journal shouldn’t let in, but if it does, they should fix it. But it is my understanding that the journal has refused to publish a clarification of these numbers.

Gun shows are not an important source of guns for criminals. Justice Department surveys of criminals indicate that fewer than 1 percent of such guns are obtained at a gun show. Instead, the vast majority of crime guns come from illegal purchases off the street, something exceedingly difficult to control.

A second piece in the same issue, by Julie Cantor, describes the effects on crime from the 2008 District of Columbia v. Heller Supreme Court decision in the following way: “Dire predictions have not yet been realized.” This suggests that there is inevitable misfortune yet to come. The New England Journal of Medicine published articles and editorials prior to the 2008 Heller decision warning about a crime wave, so the journal ought to have a serious discussion about the actual outcome. We can easily understand why such an examination would prove embarrassing. No one would guess from their discussion that D.C.’s murder rate fell by 23 percent in 2009 and continued falling sharply in 2010, several times faster than the drop in murder in the rest of the nation.

Eventually even the subscribers to the New England Journal of Medicine will learn about these facts. Just look at the changes in the climate debate — not even the most prestigious places can get away with biased research for too long.

— John R. Lott Jr. is a FOXNews.com contributor, an economist and author of the recently revised third edition of More Guns, Less Crime.