mui dui admission and charges

have friend who when recently pulled over was accused of not stopping at two stop signs. after admission of drinking 1 beer earlier in the day a field sobriety test was failed, the breathalizer exam was refused and it was later discovered that the questioned was a minor. does admission of consumption of alcohol secure the minor under the influence charge? the circumstances of the dui charge vary. other than the failed standing count and eye exam no breathalizer was given. can that charge be questioned and dropped?
thanks for the advice