The problem is, some of Buchanan's "facts" are mere factoids. Let's take one of the most stubborn factoids to emerge in the immigration debate, one that Buchanan cites as do other commentators: 95 percent of all the outstanding homicide warrants in Los Angeles, which total 1,200-1,500, are for illegal aliens. Sounds pretty damning, that is until you try to pin down where it came from and what it means.

I've been tracking this particular factoid for a while, since it crops up over and over again, and I've even exchanged e-mails with the source, Heather Mac Donald of the Manhattan Institute. In 2004, Mac Donald wrote an article for the Manhattan Institute's City Journal, "The Illegal Alien Crime Wave," in which she first used this statistic.

The problem is, the Los Angeles Police Department doesn't collect information on the immigration status of criminals, much less suspects, so there is no database of how many illegal aliens are wanted on outstanding homicide warrants. When I asked Mac Donald to provide her source, she said, "The LAPD fugitive warrants section gave me that figure." I don't doubt Mac Donald's word — she is an old friend. Someone, Mac Donald won't say who, undoubtedly gave her this misinformation. But several calls to the LAPD elicited the same response: We don't collect such information — which was borne out by searching all available databases and talking to respected criminologists.

This particular factoid has been debunked by several sources, including the Los Angeles Times and Snopes.com, but it just won't die. And other factors make the statistic highly suspicious. In all of 2004, there were only 518 homicides in Los Angeles, suggesting that the number of outstanding warrants (no matter whom they are for) must date back over many years, unless we are to assume that all murders in 2004 were committed by at least two illegal aliens and that no one was ever been arrested for any recent homicide.

The statistics on immigrants and crime are shocking — but not for the reasons Buchanan et al. would have you believe. It's hard to pin down statistics on how many crimes are committed by immigrants (or all Hispanics, for that matter) because the Bureau of Justice Statistics (the largest source of data) collects information broken down by race and gender, but not ethnicity or country of birth. However, it is possible to examine who's in jail or prison by nativity, which should be a pretty good proxy for determining who is committing serious crimes. And when you look at this data, the results are little short of amazing.

University of California professor Ruben Rumbaut, an expert on immigration and crime, looked at 2000 Census data on the institutionalized population in the United States, most of whom are in prisons, and came up with these astonishing facts. Immigrants are far less likely to be in jail or prison than other U.S. residents (the database covers federal, state, county and local prisons and jails). Of the U.S. population of 45.2 million men ages 18-39 (those most likely to be in the criminal population), 3 percent were incarcerated, or about 1.3 million at the time of the 2000 Census. But of these, blacks, whites and U.S.-born Hispanics had incarceration rates that dwarfed those of immigrants. Only .7 percent of Mexican-born males were in prison or jail, compared with 3.51 percent of all U.S.-born males, which includes 1.71 percent of non-Hispanic whites, 11.6 percent of blacks and 5.9 percent of Mexican Americans. Indeed, for all foreign-born groups, immigrants have lower incarceration rates than all U.S.-born racial and ethnic groups do, including whites.

But these facts have yet to banish the factoid that immigrants commit more crimes than the native born. And you can bet that demagogues like Buchanan will continue to ignore the facts and repeat the factoids.