When someone accuses you of something, then takes it back, that accuser is said to have "recanted." Recantations turn up most commonly in domestic abuse or sex assault cases. The recanting accuser may say either no it never happened, or yes it happened but for one reason or another you should not be blamed.
Does a Recantation Force the Prosecutor to Drop the Charge(s)?
You might think a recantation would be the end of the case against you right there. Sometimes but not always. In fact, recantations are so common that prosecutors often have an expert witness on call, usually a psychologist, counselor, or social worker of some sort, to testify about reasons that victims recant. A real victim may falsely claim the crime did not happen after all, or that it was all a misunderstanding, or any number of variations that attempt to excuse the defendant. Prosecutors and their experts have standard scripts they follow, modified to fit the particular case. Sometimes they present a diagnostic profile so broad that no matter what the facts are, the defendant must be guilty. This, of course, can be pointed out as "heads we win, tails you lose" nonsense. In most if not all jurisdictions, it is no longer true the accusing party can drop the charges. Only the judge can do that, and generally only on motion or stipulation of the prosecutor.
What Factors Decide Whether the Recantation Will Matter
If the prosecution is highly dependent on the testimony of an accuser or other witness, and that person will not cooperate, the prosecutor may be forced to ask the judge to drop the charges. Otherwise, it all depends on what the overall evidence and circumstances suggest. Was the accuser telling the truth at first, or is she telling the truth now? Did she lie then, or is she lying now? What motivations would she have to falsely accuse you? What motivations would she have to lie now to get you off the hook? Neither your defense nor the prosecutor needs to show motive about anything, but it generally helps if you can. Is it all he said-she said? What do other witnesses, if any, have to say about what happened? What other evidence may support one story or another?
Maybe you and your girlfriend have a real bond but also some rocky days, and one day you get rougher than you meant to and she gets hurt. You drive her to the ER, the police get wind of this, and now you're charged with battery, perhaps substantial battery. But the two of you have a child, your girlfriend needs your financial support, she doesn't want you convicted or punished, so she changes her story to protect you even though you did hit her. Alternatively, maybe you and your girlfriend get into a spat because (she thinks) you had been flirting with another lady. The fight gets heated, the neighbors call the cops, and when the cops arrive your girlfriend tells them you smacked her. You then get arrested for battery and disorderly conduct. Later your girlfriend has calmed down and sets the record straight, or at least tries to set it straight.
How the Right Attorney Can Help
First and always, find an attorney whom you connect with. When facing a criminal charge, you want a proven trial attorney with a track record of great results in tough cases. An attorney who will do the full investigation the police should have done but often don't. When the facts in your case involve a recantation, you need an attorney who understands how prosecutors, judges, and juries evaluate recantations, and what works for the defense. An attorney who knows how to deflate overblown conclusions from police detectives and recantation experts.