If you want to learn about urban street gangs there are many, many ways to get this information. Cable channels like NATGEOTV and Discovery devote a huge chunk of their programming dollars to this subject with documentary-style shows that cover most of the major street gangs and profile some of the more prominent gang members; often including commentary from OG's (Original Gangsters, a/k/a senior or founding gang members).
There is a wealth of information on the Internet. Type a few key words relating to street gangs into the search engine of your choice and within seconds, you'll have access to more information than you can digest in a month. Please note, I'm not endorsing any of the web sites which appear in this post. They are included for illustrative purposes only.
This information runs the gamut from law enforcement websites USDOJ Office of Justice Programs and US Bureau of Justice Assistance which publish treatises such as the Gang Prosecution Manual and Urban Street Gang Enforcement (here are the links):
to informational websites aimed at providing general knowledge of gang culture and gang prevention
When you consider all of the "authoritative" Internet data, as well as everything relating to gangs posted on social networking, video sharing sites and personal web pages; it possible to get a very good idea of what gang history, culture and organization is all about. To be sure, intimate knowledge of gang life is granted only to a privileged few but in many ways urban street gangs are more transparent than organizations like the Masons or the Elks.
So why is it that the various "gang investigator associations" restrict general membership to law enforcement, probation, corrections and prosecutors? Why is that defense investigators can't join these groups and receive the same training? What is the big secret?
I think the big secret is that by limiting this "gang training" to law enforcement and associated professions, a police "gang expert" who is "certified" is assumed to be more credible than a defense witness testifying in the same subject area but based his or her own area of gang expertise. In the DOJ Gang Prosecution Manual's section on "Gang Expert Qualification", two of the qualifiers relate to membership in a gang investigator's association.
Interestingly, it appears that many of the other qualifiers listed in this section also apply to the defense, especially for an investigator who has had substantial contact working with gang members. Anyone familiar with the story of graduate student, Sudhir Venkatesh, currenty a sociology professor at Columbia University will realize that working closely with gang members in any capacity can build expertise on gang life.
For those of you not familiar with this story, the short version is that while he was working on a study of race, poverty and crime, Venkatesh was held captive by a gang for two days. He was not harmed and eventually developed a rapport with the leader of the gang, giving him unprecedented access to the gang's inner workings. A longer version of the story can be found in Freakonomics by Levitt and Dubner in the chapter entitled Why Do Drug Dealers Live With Their Mothers?
The question of "who is an expert?" may become moot in the not too distant future. I've heard from some gang detectives that in certain jurisdictions, law enforcement investigators are beginning to eschew the notion that someone is a "certified gang expert," because the nature of the urban street gang is constantly in a state of flux. Gang identifiers (like colors or signs) change as gangs evolve, adapt to changes in the community, merge, regroup or dissolve. The expert title is becoming too difficult to maintain.
In the end, it's important to understand the basic Who, What, Why and How of urban street gangs, if for no other reason than it may help us to better communicate with the client accused of a gang related crime.