SUMMARY
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We have documented what is known about how people obtain firearms
for criminal activities and identified the weaknesses of existing evaluations
of interventions. There is not much empirical evidence that assesses whether
attempts to reduce criminal access to firearms will reduce gun availability
or gun crime. Most research has focused on determining whether prohibited
persons illegally obtain firearms from legitimate commerce (legal primary
and secondary markets) or whether crime guns are stolen or acquired
through informal exchanges. Current research evidence suggests that illegal
diversions from legitimate commerce are important sources of guns and
therefore tightening regulations of such markets may be promising. There
also may be promising avenues to control gun theft and informal transfers
(through problem-oriented policing, requiring guns to be locked up, etc.).
We do not yet know whether it is possible to actually shut down illegal
pipelines of guns to criminals or what the costs of such a shutdown would
be to legitimate buyers. Answering these questions is essential.
We also provide an analytic framework for assessing interventions.
Since our ultimate interest is in the injuries caused using guns and not how
guns are obtained, the key question involves substitution. In the absence of
the pathways currently used for gun acquisition, could individuals have
obtained alternative weapons with which to wreak equivalent harm?
Substitution has many dimensions; time, place, and quality are just
some of them. For example, that crime guns tend to be newer than guns
generally indicates that criminals prefer new guns, even though old guns are
generally as easy to get and are cheaper. This may be strictly consumer
preference, or it may be to avoid being implicated, through ballistics imaging,
in other crimes in which the gun was used. Would offenders currently
using newer guns use older guns—or any guns—if access to newer guns
became more limited? If particular dealers account for a disproportionate
share of crime weapons, then we are left with yet another version of the
substitution question: Would the criminals have obtained other guns, with
similar harmful effects, from other sources, including other FFLs? How
long would this process of substituting from new to old or from one source
to another take?
What data are needed to determine the extent of substitution among
firearms? Much could be learned from individual-level data from a general
population survey on the number of guns owned by length of time, along
with detailed individual characteristics of the individual (age, demographic
characteristics, psychiatric history, other high-risk behaviors), along with
type of gun owned (if any) and the method of acquisition (retail purchase,
legal purchase of used gun, illegal purchase of stolen gun, borrowed through
informal network). In addition, one would want measures of the availabil100
ity of firearms of each type to potential buyers of each type in each locale.
For adults without criminal records, for example, there are established,
observable prices of new guns at retail outlets. Similarly, there are active
markets in used guns, for which there are (at least in principle) prices. The
prices are individual specific in the sense that, for example, juveniles and
felons cannot purchase guns at Wal-Mart.8 In effect, they face an infinite
price of guns through this channel.
Beyond this information one would also need a source of exogenous
variation on the difficulty of obtaining guns through different channels.
While guns available to legal buyers through retail outlets have literal prices,
the measures of the difficulty of gun acquisition through some other channels
are prices only in a metaphorical sense. When a city undertakes an
intervention at a particular point in time, for example to make it more
difficult for juveniles to get guns from interstate traffickers in new guns,
then (provided that the policy has some effect), it is as if the price of guns to
juveniles has risen. Provided that the timing of the intervention is independent
of the time pattern of local gun use, we could treat it as an exogenous
increase in the metaphorical price of a gun to juveniles; money prices may
fall as other costs rise because this increase in nonmoney costs shifts the
demand curve down. What happens to the tendencies for juveniles to obtain
guns; do they substitute purchases of guns stolen from homes for the
new guns they had previously purchased from traffickers? Is the substitution
complete? That is, is the volume of juvenile gun use as high in the
presence of the intervention as it was in the absence of the intervention?
The biggest potential problem with this framework, however, is the
assumption of an exogenous intervention. No real intervention is likely to
be exogenous; that is, unrelated to changes in gun crimes. It might be more
realistic to think about exogeneity conditional on some specified set of
covariates, but the prospects for finding consensus on the correct set of
covariates to credibly maintain this independence assumption are unknown.
Alternatively, researchers may be forced to rely on other methodological
approaches and data.
The committee has not attempted to identify specific interventions,
research strategies, or data that might be suited for studying market interventions,
substitution, and firearms violence. The existing evidence is of
limited value in assessing whether any specific market-focused firearm restrictions
would curb harm. Thus, the committee recommends that work be
started to think carefully about the prospects for achieving “conditional
exogeneity,” the kinds of interventions and covariates that are likely to
8We ignore for the moment corrupt agents at retail outlets, viewing them as the equivalent
of straw purchasers.
satisfy this independence requirement, how one could gather the data, the
potential for building in evaluation at the stage of policy change, and other
possible research and data designs. Future work might begin by considering
the utility of emerging data systems, described in this report, for studying
the impact of different market interventions, This type of effort should be
take place in collaboration with a group of survey statisticians, social scientists,
and representatives from the Bureau of Justice Statistics and the National
Institute of Justice.