A California Serna motion (also known as a speedy trial motion or a speedy trial demand) is a kind of pretrial motion--that is, a motion that you and your criminal defense attorney can file before your actual trial begins. Serna motions are filed in cases where there has been an unusual delay in bringing the defendant to trial. If the delay is determined to violate his/her right to a speedy trial, then the criminal charges must be dismissed.