Published November 11, 2002, in The National Review
Bullets and Bunkum
The futility of 'ballistic fingerprinting.'
By John R. Lott Jr.
In the wake of the Washington, D.C., sniper attacks, many are viewing
ballistic fingerprinting as a magic crime-solving tool. According to
the pro-gun-control Brady Campaign, such a system "would have solved
[the sniper case] after the first shooting"; a Washington Post
columnist calls it a "common-sense measure"; and many politicians are
jumping on board, including New York Democratic senator Charles Schumer
and Maryland Democratic gubernatorial nominee Kathleen Kennedy
Townsend. Unfortunately, the issue is not so simple: By draining
resources away from other police activities and making it costly for
law-abiding citizens to own guns, ballistic fingerprinting could end up
actually increasing crime.
The physics of ballistic fingerprinting are straightforward. When a
bullet travels through the barrel of a gun, the friction creates
markings on the bullet. If the gun is new, imperfections in the way the
barrel is drilled can produce different markings on the bullet; such
imperfections are most noticeable in inexpensive guns. (This poses an
irony for gun controllers, who push for laws that ban inexpensive
guns.) In older guns, the bullets' friction through the barrel can
cause more noticeable wear marks that help differentiate between guns.
Many other factors influence the particular markings left on the
bullets - for instance, how often the gun is cleaned and what brand of
cartridge is used.
Precisely because friction causes wear, a gun's ballistic fingerprint
changes over time - making it drastically different from such forensic
evidence as human fingerprints or DNA. The recording of a child's
fingerprints or DNA still allows for identification much later in life;
the same is not true of the bullet markings. A ballistic fingerprint is
less like a human fingerprint than it is like the tread on a car tire.
Brand-new tires are essentially identical, so new-tire tracks at crime
scenes leave investigators with pretty limited information. Unless
there happens to be a particular imperfection, only the brand and model
of the tire can be identified. Imprints on bullets are similar. When a
bullet is fired from a new gun, investigators can typically identify
only the type of ammunition and the type of gun. Over time, though,
friction causes the tread on tires to wear. It would be easy to take
the tire tracks left at a crime scene and match them with a suspected
criminal's car; but the more the car is driven after the crime, the
harder it is to match the tire tracks left at the scene to the tires
when they are eventually found. Similarly, the greatest friction on a
gun occurs when the gun is first fired - and that dramatically reduces
the usefulness of recording the gun's ballistic fingerprint when it is
Moreover, ballistic fingerprinting can be thwarted by replacing the
gun's barrel - just as criminals can foil tire-matching by simply
replacing their tires. In general, the markings on bullets can be
altered even more quickly and easily than the tread marks on tires:
Scratching part of the inside of a barrel with a nail file would alter
the bullet's path down the barrel and thus change the markings. So
would putting toothpaste on a bullet before firing it.
Ballistic fingerprinting faces other difficulties. For example, even if
the gun was not used much between the time the ballistic fingerprint
was originally recorded and the time the crime occurred, police still
have to be able to trace the gun from the original owner to the
criminal - but only 12 percent of guns used in crime are obtained by
the criminal through retail stores or pawn shops. The rest are
virtually impossible to trace.
So far only Maryland and New York have started recording the ballistic
fingerprints of all new handguns sold. While Maryland's program
technically started in January 2001, the cost of implementing the
program made it unprofitable for gun makers to sell handguns in the
state for the first six months of that year. The state government faced
a $1.1 million start-up cost and another $750,000-a-year operating
cost. New York's program began in March 2001, with a state start-up
expenditure of about $4.5 million. (No estimates are available yet on
New York's annual cost.)
In both states, the costs for dealers, gun makers, and prospective gun
owners were responsible for reducing handgun sales to law-abiding
citizens. And what was the specific benefit? Almost zero. The programs
have not helped solve a single violent crime in either state; they have
so far been used only to identify two handguns stolen from a Maryland
A recent study by the State of California points to further practical
difficulties with ballistic fingerprinting. The study tested 790
pistols firing a total of 2,000 rounds. When the cartridges used with a
particular gun came from the same manufacturer, computer matching
failed 38 percent of the time. When the cartridges came from different
manufacturers, the failure rate rose to 62 percent. And this study does
not even begin to address problems caused by wear, so the real-world
failure rate can be expected to be much higher. The California report
warned that "firearms that generate markings on cartridge casings can
change with use and can also be readily altered by the users." Further,
it warned that the problems of matching would soar dramatically if more
guns were included in the sample. The study's verdict:
"Computer-matching systems do not provide conclusive results . . .
potential candidates [for a match must] be manually reviewed."
While registering guns by their ballistic fingerprints is a relatively
new concept, we have had plenty of experience using gun registration in
general, and it has come up woefully short. A couple of years ago, I
testified before the Hawaii state legislature on a bill to change
registration requirements. Hawaii has had both registration and
licensing of guns for several decades.
In theory, if a gun is left at the crime scene, licensing and
registration will allow the gun to be traced back to its owner. Police
have probably spent hundreds of thousands of man-hours administering
these laws in Hawaii. But despite this massive effort, there has not
been a single case in which police claimed that licensing and
registration have been instrumental in identifying a criminal.
The reason is simple. First, criminals very rarely leave their guns at
a crime scene, and when they do, it is because the criminals have been
killed or seriously wounded. Second - and more important for ballistic
fingerprinting - would-be criminals also virtually never get licenses
or register their weapons. The guns that are recovered at the scene are
Good intentions don't necessarily make good laws. What counts is
whether the laws actually work, and end up saving lives. On that
measure, ballistic fingerprinting - a useless diversion of valuable
police resources - fails conspicuously, and it should be opposed by
anyone who wants to live in a safer society.
Mr. Lott, a resident scholar at the American Enterprise Institute, is
the author of More Guns, Less Crime.
Updated Media Analysis of Appalachian Law School Attack
Since the first news search was done additional news stories have been
added to Nexis:
There are thus now 218 unique stories, and a total of 294 stories counting
duplicates (the stories in yellow were duplicates): Excel file for
general overview and specific stories. Explicit mentions of defensive gun use
increase from 2 to 3 now.