With crime rates in Los Angeles and other cities plummeting, many analysts say at least part of the reason lies with with demographic trends: The population is aging and the ranks of crime-prone juveniles and young adults have been dropping for more than a decade.
"Age is a critical concern," said James Alan Fox, a criminologist at Northeastern University in Boston, who has long argued the connection between age and crime rates. "Most street criminals and violent offenders are young and aggressive."
The seemingly logical explanation holds a special resonance in Los Angeles, where the number of people in the 15- to 24-year-old age bracket--widely considered those most likely to break the law--plunged by 23% between 1990 and 1996, census data show.
Although Los Angeles remains young by national standards, that drop here was almost four times the 6.3% national rate of decline for 15- to 24-year-olds.
But however neatly it seems to fit the circumstances, the age argument is highly disputed and, critics say, widely overstated. It is every bit as contested as sundry other explanations--from smarter police tactics to more prisons and jails--that have been floated and often hyped to explain what remains a stubbornly mystifying drop in crime nationwide for five consecutive years.
"Crime is enormously complex, and trying to explain with one pat theory--that more kids mean more crime--is not only wrong, it's misdirecting our policy," said Michael Males, an Orange County-based researcher who argues that the young are demographic scapegoats for crime.
UCLA crime expert James Q. Wilson said: "Age is a significant factor, but it is not the only factor and is not the single dominant factor."
In a very broad sense, crime does present an indisputable demographic fingerprint. There is no question that men commit the vast majority of crimes. And according to the U.S. Justice Department, 95% of all arrests involve suspects between the ages of 10 and 49.
However, statistical quirks make easy correlations impossible. For example, although the decline in the number of 15- to 24-year-olds in Los Angeles was several times greater than the national decline, that drastic shift was not reflected a comparison of local and national crime rates.
In the late 1980s, the popular demographic theory linking juveniles and young adults to crime rates suffered a major setback: Youth crime soared even as the youth share of the population declined.
Wilson, a UCLA professor of management and public policy who who sees a clear link between crime and demographics, said: "I was caught flat-footed."
But he and others now say that an unanticipated factor--the explosive emergence of crack cocaine in the mid-1980s and the attendant violence in inner-city America--drew youths into criminality, especially violent crime, at levels impossible to foresee.
"It was unpredictable that crack cocaine would hit the streets," said Fox, dean of Northeastern's College of Criminal Justice.
Today, many experts across the political spectrum are citing the decline of crack and other drug markets and an accompanying drop in street violence as a major reason for plunging crime statistics. Those changes would seem to mesh with recent trends in juvenile offenses.
Arrests of juveniles for violent crimes nationwide rose steadily beginning in 1987, as crack cocaine spread widely, until finally dropping 4% in 1995. Atty. Gen. Janet Reno trumpeted the 1995 decline as evidence that authorities could indeed take concrete steps to discourage youth crime.
"Demographics do not have to be destiny," Reno said.
She credited the decline largely to enforcement tactics--such as the use of community-based policing, and "holding youth accountable for every act--including their first offense." Critics dispute the impact of enforcement on the drop in youth crime, citing other factors, such as declining violence associated with drugs.
Whatever the reason, it is clear that youth by itself is far from an infallible indicator of crime rates.
On one level, experts note, change in age structure is by definition gradual and incremental, unfolding over years and even decades. Barring unusual circumstances, the overall age of the population does not undergo dramatic alterations in a single year or so. Crime statistics, by contrast, are infamous for sudden shifts--this year's FBI Uniform Crime Report found that murder dropped 11% nationwide in 1996, while violent crime dropped 7%.
The city-by-city breakdown of the FBI report also underscores another weakness of age-based analyses: Such efforts often fail to explain distinct regional differences.
Last year, the FBI data showed, most large cities experienced significant declines in reported crimes. Los Angeles' serious crime rate fell 11.6%, while New York's dropped 13.8%. But crime did not go down everywhere.