Form 12 — Application for Leave to File Second or Successive Petition Under 28 U.S.C. Sec. 2254 or Motion Under 28 U.S.C. 2255 is a form used by individuals who have been convicted of a federal crime and wish to file a second or successive petition or motion to their case. The form is used to determine whether an individual has met the requirements for filing a second or successive petition or motion under 28 U.S.C. Section 2254 or 2255 and, if so, to grant the individual leave to file such a petition or motion. There are two types of Form 12 — Application for Leave to File Second or Successive Petition Under 28 U.S.C. Sec. 2254 or Motion Under 28 U.S.C. 2255: (1) Form 12A for an Application for Leave to File a Second or Successive Petition Under 28 U.S.C. Sec. 2254; and (2) Form 12B for an Application for Leave to File a Motion Under 28 U.S.C. Sec. 2255.