Each agency/jurisdiction responds to complaints differently. It's difficult to give a precise answer, as there are multiple factors involved. 1. Your friend says you hit her. She makes an official report. The police will contact you to get your side of the story. You deny hitting her & there is no evidence to support her claim such as bruising, redness, witnesses, etc. You both have conflicting stories. You would likely both be issued citations to appear before the judge, meaning no arrests are made, as the officer is unable to determine who is telling the truth. So basically, you go & tell it to the judge. Usually in those cases, the judge tells you both to grow up & stay away from one another. 2. If there IS evidence to support her claim, at that point, it is pretty much officer discretion. He can either charge you or issue a citation to appear. If the injuries are consistent with what she says you did, you are more likely to be arrested & charged with misdemeanor battery.