You can sue an arresting agency with respect to the facts that you have written about where you were arreste, sat in jail fpr six months and then the case was thrown out of court. Whether or not you prevail on a lawsuit for false arrest or some other theory of recovery is an unknown at this point.In order to ascertain whether or not you have a valid basis for bringing a lawsuit against the arresting agency, you should consult with an attorney who represents individuals in false arrest cases which seems to be what your matter is about.