Academic Legal Writing - Eugene Volokh [182]
2. Inferring from a group's behavior to the behavior of a subset of the group: The study focused on behavior among drivers aged 16 to 25, but the commentator is inferring that “driving-age teenagers”—which readers might interpret either as 16–to–18–year-olds, which is what the law refers to, or 16–to–19–year-olds, which is what “driving-age teenagers” literally means (assuming the driving age is 16)—will behave the same.
This inference may or may not be correct. It may be that 16–to–18–year-olds drink and drive more than 16–to–25–year-olds generally, because they're less mature—or less than 16–to–25–year-olds generally, because they can't legally buy alcohol, or because they're less likely to own a car. In any event, the commentator should again make clear the assumption that he is making.
3. Misreporting the study: Finally, the commentator errs in reporting one aspect of the study—the study reported that 15% of New York drivers aged 16 to 25 drove drunk at least once a month, not that 15% of 16–to–25–year-olds drove drunk at least once a month. The commentator's ultimate position may be right: There may be a serious drinking and driving problem among Minnesotan teenagers, and perhaps the law will help fight that. But the errors and omissions in reporting the study need to be corrected.
E. Source–Checking Exercise, p. 190
Let's quickly repeat the sources.
The student article:
Proponents of manufacturers' liability further argue that handguns are almost useless for self-protection: a handgun is six times more likely to be used to kill a friend or relative than to repel a burglar, and a person who uses a handgun in self-defense is eight times more likely to be killed than one who quietly acquiesces. [Footnote cites source A.]
Source A (which was indeed written by a proponent of manufacturers' liability, so no need to check that), quoted in relevant part:
The handgun is of almost no utility in defending one's home against burglars. A Case Western Reserve University study showed that a handgun brought into the home for the purposes of self-protection is six times more likely to kill a relative or acquaintance than to repel a burglar. [Footnote cites source B.] .... The handgun is also of questionable utility in protecting against robbery, mugging or assault .... The element of surprise the robber has over his victim makes handguns ineffective against robbery .... A survey of Chicago robberies in 1975 revealed that, of those victims taking no resistance measures, the probability of death was 7.67 per 1000 robbery incidents, while the death rate among those taking self-protection measures was 64.29 per 1000 robbery incidents. [Footnote cites source C.] The victim was 8 times more likely to be killed when using a self-protective measure than not!
Although handguns possess little or no utility as self-protection devices, some may have a socially acceptable value when properly marketed under restricted guidelines [such as to the police].
Source B (the Case Western study), quoted in relevant part:
During the period surveyed in this study [1958–73 in Cuyahoga County, Ohio], only 23 burglars, robbers or intruders who were not relatives or acquaintances were killed by guns in the hands of persons who were protecting their homes. During this same interval, six times as many fatal firearm accidents occurred in the home.
Source C, the Chicago robbery study, quoted in relevant part:
Of those victims taking no resistance measures, the probability of death was 7.67 per 1000 robbery incidents, while the death rate among those taking self-protection measures was 64.29 per 1000 robbery incidents.