Nominally this was a response to incidents throughout the rest of the state such as Columbine, but in reality the purpose was to try to combat youth gangs. In this respect I think it partially worked for the circumstances.
However, this was also used to target usage of marijuana and cigarettes by students. I'm not sure how effective this was, because data about that was not commonly released by the school. Needless to say, a lot of students didn't like this, but opinion of the student body was very divided. It would be interesting to see how things have changed in Colorado high schools since marijuana was legalized; I'll have to look into that, but in most schools marijuana is still banned (like tobacco products) so things could only get worse if school policy is unchanged.