According to this article from the New York Times today, policy makers and law enforcement leaders in jurisdictions such as Los Angelos and Texas that pioneered hard-hitting anti-gang tactics in the nineties (which included laws prohibiting two or more gang suspects from congregating in a public place, broad sweeps of suspects, and long jail sentences for gang-related crimes) think those tactics may have worsened the problems they were meant to solve by alienating poor communities from the police and hardening juvenile delinquents into serious criminals. Now, they're focusing their strategies and funding priorities on prevention, intervention, and rehabilitation. For an interesting example of what that means to the court system, and a question about the issue of culture read more.
The article cites an example of a young man, 16, who was arrested for possesing a knife at his local public school, and then arrested a second time for being high on marijuana at his alternative state school. It was only after these arrests that he decided to join a gang and commit an unarmed robbery along with several other young men. These types of charges are viewed as "minor" within the courts. While media attention and decision-making is driven by high profile killings, it is the response that the justice system makes to these low-level criminal offenses that might have the biggest impact on the gang problem.
The article also raises the issue of culture. Officials and community leaders are quoted wondering how police and communities should react when young people who are not necessarily gang affiliated wear gang style clothing and make gang gestures.
For more on the topic, the website of the National Gang Center (a joint project between between the Office of Justice Programs’ (OJP) Bureau of Justice Assistance (BJA) and the Office of Juvenile Justice and Delinquency Prevention (OJJDP) is a good resource.