TITLE IV. ARRAIGNMENT AND PREPARATION FOR TRIAL
Rule 11. Pleas
(a) Entering a Plea.
(2) Conditional Plea. With the consent of the court and the government, a defendant may enter a conditional plea of guilty or nolo contendere, reserving in writing the right to have an appellate court review an adverse determination of a specified pretrial motion. A defendant who prevails on appeal may then withdraw the plea.
National proceedings on admission of guilt
EDIT.