http://www.youtube.com/watch?v=VqtPUhYdz6M
Monday, a 17-year-old named Steve Consalvi ran onto the field at Citizens Bank Park. Wearing a red shirt and khaki pants, he ran around waving a white towel above his head, a police officer Tasered him. The incident raises some interesting legal issues. Foremost, are police officers using excessive force when they use a Taser who have run on the field of play. The answer, not surprisingly, is ... that depends.
http://mlb.fanhouse.com/2010/05/04/legal-analysis-was-tasering-phillies-fan-excessive-force/