Defendants shall have the right to a jury trial in all criminal prosecutions, including prosecutions for violations of traffic laws, in the District Court. A defendant may request a jury trial at any time prior to the time his or her case is called for trial. Any waiver of a defendant's right to a jury trial shall be in writing. Once a defendant asserts his or her right to a jury trial, the request may not be withdrawn over the objection of the Commonwealth and permission of the Court.