8 CFR § 223.3 - Validity and effect on admissibility.
(a) Validity—(1) Reentry permit. Except as provided in § 223.2(c)(2), a reentry permit issued to a permanent resident shall be valid for 2 years from the date of issuance. A reentry permit issued to a conditional permanent resident shall be valid for 2 years from the date of issuance, or to the date the conditional permanent resident must apply for removal of the conditions on his or her status, whichever comes first.
(2) Refugee travel document. A refugee travel document shall be valid for 1 year, or to the date the refugee or asylee status expires, whichever comes first.
(b) Invalidation. A document issued under this part is invalid if obtained through material false representation or concealment, or if the person is ordered excluded or deported. A refugee travel document is also invalid if the United Nations Convention of July 28, 1951, ceases to apply or does not apply to the person as provided in Article 1C, D, E, or F of the convention.
(c) Extension. A reentry permit or refugee travel document may not be extended.
(d) Effect on admissibility—(1) Reentry permit. A permanent resident or conditional permanent resident in possession of a valid reentry permit who is otherwise admissible shall not be deemed to have abandoned status based solely on the duration of an absence or absences while the permit is valid.
(2) Refugee travel document—(i) Inspection and immigration status. Upon arrival in the United States, an alien who presents a valid unexpired refugee travel document, or who has been allowed to file an application for a refugee travel document and this application has been approved under the procedure set forth in § 223.2(b)(2)(ii), shall be examined as to his or her admissibility under the Act. An alien shall be accorded the immigration status endorsed in his or her refugee travel document, or (in the case of an alien discussed in § 223.2(b)(2)(ii)) which will be endorsed in such document, unless he or she is no longer eligible for that status, or he or she applies for and is found eligible for some other immigration status.
(ii) Inadmissibility. If an alien who presents a valid unexpired refugee travel document appears to the examining immigration officer to be inadmissible, he or she shall be referred for proceedings under section 240 of the Act. Section 235(c) of the Act shall not be applicable.