To begin the process of vacating a conviction in California, your attorney must file a motion to vacate. If you can demonstrate that you did not understand the consequences of your plea, that you were coerced, or that you were not adequately represented in court, the judge may grant this motion and begin the trial anew from the point of arraignment. This will allow you to enter a new plea and, ideally, avoid the conviction that was the result of the original trial.