Fundamentally graffiti is more than "an element of youth culture," just look at what we know of ancient societies from the graffiti messages that remain.
Obviously not all graffiti constitutes thoughtful communication and the “tagging” that seems to have prompted the drafting of the policy is a distinct issue.
However, a definition that recognises graffiti is illicit as well as public is important in addressing the behaviour.
A definition for street art would, in turn, recognise a variety of activities for legal expression by the community in public spaces.
As a result, I think a separate public art policy should address the availability of walls for designs and the community engagement which will foster a sense of ownership for those spaces.
It would also look broadly at resources within the community for engagement and the promotion of art.
Furthermore, a broader discussion of public art would promote the pathways available to develop skills and that such activity is not limited to a youth demographic.
Promoting graffiti would be at odds with the criminal punishment that activity.
Developing opportunities for the community to exhibit their designs and other thoughtful communication through public art would be a good outcome.
