Let's agree that the arrest of Mexican drug lord Joaquin "Shorty" Guzman is not going to have an impact on the flow of drugs through Mexico into the rest of North America.

That flow is driven by demand, and the demand for drugs in the U.S. and Canada will continue whether Guzman is in prison or out, alive or dead.

Inevitably, some will say that means the war on drugs is pointless and lost, and they will dismiss the arrest of drug kingpins as meaningless.

People disagree about what makes a sensible drug policy, but that argument does not make the arrest of Guzman meaningless.

It may well be seismic.

To understand why, try seeing it from a Mexican perspective and recognizing that the term "drug cartels" is outdated and limiting.

What we consider "drug cartels" in Mexico are more accurately "crime cartels."

They have been diversifying for years and now have revenue streams from human trafficking, prostitution, kidnapping and murder for hire.

The most brutal cartels are plainly terrorist organizations.

Each has a component of homicidal maniacs who control people through fear.

Mexico Drug War

Joaquin "El Chapo" Guzman sits inside a federal police helicopter in Mexico City, on Feb. 22, 2014. One of the world's most-wanted drug lords, Guzman is also now the subject of an extradition fight with the U.S., who want to try him as well. (Eduardo Verdugo / Associated Press)

They cut off heads and hang dead bodies from bridges because those images on television and in the newspapers are terrifying and intimidating to journalists, police, politicians and judges.  

If those things were happening in Canada, if a mother driving her son to hockey practice in Toronto had to shield his young eyes from mutilated cadavers hanging from the Gardiner Expressway, no one would argue that it was pointless to try to stop it.

The birth of narco-terrorism

So the same should be true for Mexico.

The cartels are a challenge to law, order and the authority of governments in Mexico. Consequently they are a threat to its democracy.

In the decades before multi-party elections, when the long-ruling Institutional Revolutionary Party, the PRI, could run things however it wanted and without fearing the discipline of the ballot box, a working relationship between governments and cartels was manageable.

It was understood that if the cartels kept their violence in check and intra-mural, they could go about their business with impunity. There was money for everyone in that arrangement.

But in the last generation there have been three important developments that have profoundly changed Mexico.

First, democratic reforms required Mexico's governments to be more transparent. It was still possible to deal under the table with drug lords, but it was getting harder and harder.

Second, the withering of Colombia's cartels altered the flow of drugs north. Mexico became the principal gateway for drugs from around the world into the U.S. and Canada and the dollar value of that business multiplied accordingly. (U.S. officials estimate that Guzman's Sinaloa cartel alone reaped about $3 billion a year from drug trafficking.)

Third, probably as a result of the first two conditions, cartel violence turned more sadistic and less discriminate. Narco-terrorism was born.

Choosing sides?

In 2006, voters elected Felipe Calderon president and he made fighting drug violence his priority. In fact, he sent the Mexican Army to war with the cartels.

By the time he left office in 2012, a modest estimate of the human toll from the war was 60,000 dead.

Tellingly, despite his determination to free Mexico from the grip of the cartels, his own drug czar was charged in 2008 with taking bribes of $450,000 a month.

Harper Mexico 20140219

Mexican President Enrique Pena Nieto hosted Barack Obama and Stephen Harper at the North American Leaders Summit in Toluca, Mexico, in February. Three days later his world changed when Shorty Guzman was captured. (Canadian Press)

Calderon's successor, President Enrique Pena Nieto, led the PRI back to power in part by promising a fresh approach to the drug war.

He said he didn't think pursuing drug kingpins was an effective way to stop their violence, so he wasn't going to do it.

To many, Pena Nieto's fresh approach seemed more like a throwback to the old way of doing things.

Some in Mexico called it "pax mafiosa" an Italian phrase for the "live and let live" accommodation between governments and cartels, and they believed there was evidence of that.

Guzman's lieutenants had reportedly ordered their commanders to ease up on their murderous ways in Baja, Calif., so as not to draw attention and heat from the Federales.

Another twist came with the arrest last July of a rival drug lord, Miguel Trevino Morales, a psychopath with the bloodthirsty Zetas.

It began to look as though the government had chosen a side, that it would work with Sinaloa against its rivals, and that Guzman's Sinaloa would have a free hand to pursue its "business" interests.

That scenario fit easily into the makeover of Guzman's image from murderous drug lord into a kind of modern-day Robin Hood.

In the state of Sinaloa he has become a folk hero, with his generous community work celebrated in song and his apparent immunity from prosecution believed to have been guaranteed by high authority.

Around Sinaloa, few believe Guzman was really living on the lam all those years after his escape from a maximum security prison in 2001.

They believe that was only a cover story police spread around to make it sound like they were on his trail.

A new book even claimed there was a videotape that proved Guzman's escape from prison in a laundry cart was just a cover for the real story — that he walked out disguised as a policeman, and with a police escort.

Yet now Guzman, too, is behind bars.

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Mexico's drug war has expanded to private groups, like these community police who ride through the streets of Apatzingan, in western Mexico, helping the army track down members of a local drug cartel known as the Knights Templar. (Edgard Garrido / Reuters)

That could mean that Pena Nieto now sees that modern Mexico will only become a mature democracy if it refuses to tolerate any challenge to the authority of elected governments.

Even in Sinaloa, even from Guzman.

It could also mean the U.S. has put pressure on Pena Nieto to give up on the live-and-let-live stuff and, instead, behave more aggressively, like a real government, everywhere in the country.

Both scenarios suggest Guzman's arrest is not simply the result of good (or lucky) ­­­­­­police work, but a policy change at the top: the assertion of sovereignty at home.

Isn't that a good thing?