If one wishes an object lesson in the unintended consequences of drug prohibition, one need look no further than the other side of the Rio Grande. Like all borders, the US-Mexican border has always been the scene of a lively trade in contraband. Although the authors of "From the Maras to the Zetas: The Secrets of the Drug Trade, From Colombia to Chicago" don't get into the prehistory of Mexico's powerful drug trafficking organizations, way back in those halcyon days of the 1960s and 1970s, a lot of marijuana moved across that border, but it was a largely peaceful trade, often a family affair.

In 1982, when President Ronald Reagan, having declared a new war on drugs, sent Vice-President George H.W. Bush to Miami to head up a new effort to block the flood of Colombian cocaine flowing across the Caribbean to Florida, the Colombians adjusted by shifting smuggling routes through Mexico. The Colombian used existing smuggling networks, which since then have grown into a Frankenstein monster, not only in the eyes of the Mexican state, but also in the eyes of their Colombian counterparts, who have found themselves squeezed out of end-stage distribution to the US and the massive profits that followed.

Fueled by Colombian cocaine, American dollars, and American weaponry, in the past 20 years, Mexico's so-called "cartels" -- a misnomer for these brutally competitive trafficking organizations -- have corrupted legions of Mexican police, soldiers, and politicians, and murdered as many more. Every time the Mexican state, hounded by its partner to the north, tries to crack down on the cartels, the result is not social tranquility or the end of the drug trade, but bloody gang wars as the different organizations fight for position -- and the flow of drugs never seems to be affected.

In the past couple of years, the cartels have become so brazen and the death toll from the constant "ajuste de cuentas" ("adjusting of accounts" or "settling scores") so horrendous -- more than 1,500 last year and a like number so far this year -- that they appear to be working with impunity.

Enter Mexico City journalists Jorge Fernandez Menendez and Victor Ronquillo. With the drug trafficking groups beheading police and engaging in street battles with RPGs in Acapulco and wreaking mortal havoc along the US border, their timing couldn't be better because they aim to explain the murky workings of the Mexican drug trade. They study and report on Mara Salvatrucha, the much screamed about gang that grew out from the children of Salvadoran refugees in Los Angeles and other American cities (another lesson in unintended consequences) who learned all too well the ways of the thug life, then re-exported it back home to Central America. According to Fernandez and Ronquillo, Mara Salvatrucha controls much of the traffic in illegal immigrants and drugs -- on Mexico's southern border. But like the truly Mexican criminal organizations, its tentacles extend far to the north as well.

They also provide the skinny on the Zetas, the US-trained former anti-drug elite force that switched sides and now acts as the armed forces of Osiel Cardenas and the Gulf Cartel -- one more lesson in unintended consequences. Thanks to the paramilitary skills of the Zetas, Cardenas has been able to directly confront the Mexican state, as when his men killed six prison employees in Matamoros in early 2005 in retaliation for a federal government crackdown on imprisoned cartel leaders.

There is much, much more in between. Fernandez and Ronquillo warn that imprisoned cartel leaders spent part of their time behind bars buddying up with imprisoned leftist guerrillas and could be either learning tactical lessons or forging unholy alliances with them. Despite the apparent ideological differences between Marxist rebels and drug traffickers, the Mexican cartels have shown that when it comes to business they are nonpartisan. They will corrupt politicians of any party, make deals with whoever can benefit them, and kill those who get in their way.

The cartels circle around power. When the old-time PRI ran the government, the cartels corrupted the PRI. When the PAN government of President Vicente Fox came to power, they attempted to corrupt it, and as Fernandez and Ronquillo demonstrate, they have arguably succeeded. PANista politicians have been caught attending the funerals of leading narcos, PANista local administrations have been bought off, and the narcos even managed to place an associate in President Fox's inner circle before the taint of scandal drove him off.

But while Fernandez and Ronquillo are quite good in unraveling the mysteries of the cartels and explicating the results of decades of prohibitionist drug policy, they fail to make the leap to the next level. For them, "From the Maras to the Zetas" is a desperate wake-up call for the Mexican public and political class, a warning that the power of the cartels threatens the integrity of the Mexican state. They do not take the next step and ask if there is not a better way. But then again, they really don't have to -- the book itself is eloquent testimony to the corrupt and bloody legacy of prohibition in Mexico.

Yes, the book is only available in Spanish. It won't be much use to many of our North American readers, but Drug War Chronicle also goes out in Spanish and Portuguese, and perhaps if we can drum up a little interest here in Gringolandia, an American or Canadian publisher will print a translation. Goodness knows we get very little serious reporting up here about the Mexican drug war.

In the meantime, for you English-only speakers out there with an interest in this topic, I recommend the recent report from the Washington Office on Latin America, "State of Siege: Drug-Related Violence and Corruption in Mexico."