Mere presence of alcohol does not, by itself, support an inference of impairment.

Police officer did not have probable cause to arrest Petitioner for driving under the influence or refusing to consent to a state-administered chemical test because, while Petitioner, who had been stopped at a roadblock, admitted to drinking, the officer presented no evidence that he had seen any signs of impairment.  The mere presence of alcohol does not, by itself, support an inference of impairment.