Policymaking battles rage over weak, unenforced gun data because research is suppressed.

Evidence

Vigorous political battles are fought over questionable data based on weak, easily circumventable gun regulations that are poorly enforced. By intimidating federal agencies for funding gun research and barring them from interpreting gun-related data, Congress keeps the public uninformed about the social effects of guns in society. — Albert Bandura, Moral Disengagement, 1330