What list of evidence is required to prove 19A.50.010 OREGON STATE (ORS) charge: "Alcohol on Public Property".?

Also can I use the fact that the "COPS" were disrespectful to me, in specific the cop called me a "liar"?. AND should I fight the charge or take the plea if the plea is "a slap on the wrist"? My court date is on March 17, 2011. THX FOR THE ADVICE IN ADVANCE.