Based on the submission of new evidence, you requested an opinion concerning the validity
                  of a tribal customary adoption granted by the Children's Court of the White Earth
                  Tribal Court, White Earth Reservation, in the State of Minnesota. We previously opined
                  in this case that to establish entitlement, the applicant must submit additional evidence.
                  To that end, the applicant submitted a copy of the Customary Adoption Code as approved
                  and certified by the White Earth Reservation Tribal Council on May XX, 2005. You have
                  asked whether the subsequent documentation substantiates that the adoption was valid,
                  and whether we could now entitle K~ to child's benefits. It is our opinion that there
                  is now sufficient evidence to establish the validity of the customary adoption of
                  K~ under the adoption laws of the White Earth Band of Ojibwe.
               
               BACKGROUND
               The NH in this case, E~ , became entitled to Disability Insurance Benefits in May
                  1976, and converted to retirement benefits in November 1993. The NH and his wife,
                  F~ , a member of the White Earth Tribe, adopted a child, K~ (their granddaughter,
                  date of birth April 2003), on November XX, 2003. Documentation regarding the adoption
                  was submitted at the time the claim was filed, and an opinion was rendered by our
                  office on March XX, 2005, in which it was concluded that additional evidence had to
                  be provided to find the adoption valid, i.e., either of (1) evidence pertaining to
                  consent of the biological father, or evidence the Tribal Court would waive such consent,
                  and evidence regarding a homestudy; or (2) a copy of the Customary Adoption Code matching
                  the version reviewed and containing an enactment provision or certification. The claim
                  was disallowed, and a request for reconsideration was filed. Along with the reconsideration,
                  a new version of the Customary Adoption Code was submitted which includes a Resolution
                  certified by the White Earth Reservation Tribal Council and adopting the Code. The
                  new version of the Customary Adoption Code, which was approved and certified on May
                  23, 2005, does not match the version reviewed in our prior opinion. Along with the
                  copy of the Customary Adoption Code, the request for reconsideration also included
                  a letter from J~, Tribal Attorney for the White Earth Reservation Tribal Council.
                  In that letter, J~ asserted that K~ was customarily adopted by the NH and his spouse
                  through the White Earth Tribal Court and that, prior to the adoption, the parental
                  rights of each of K~'s natural parents were suspended pursuant to tribal law. This
                  last information differs from the information contained with the original request
                  for advice. The documents pertaining to the adoption which were previously reviewed
                  indicated that the biological father's identity was "unknown," not that his parental
                  rights were suspended. Finally, you indicated, in the original request for advice,
                  that the White Earth Reservation Adoption Program had stated its intention to continue
                  submitting claims with customary adoptions, and to adjust their adoption procedures
                  accordingly, until they are acceptable for SSA entitlement.
               
               DISCUSSION
               As we previously advised, the White Earth Tribe has exclusive jurisdiction over K~'s
                  adoption proceeding, and the laws of the White Earth Band of Ojibwe therefore apply
                  to determine whether K~'s adoption by her grandparents was valid. Adoptions of children
                  in the Tribe may be considered valid for purposes of CIB if it can be established
                  that they were either (1) valid adoptions pursuant to the Tribe's statutory adoption
                  law, i.e., the Child/Family Protection Code (CFPC), or (2) valid "customary adoptions."
                  See Memorandum from Regional Chief Counsel, Chicago, to Regional Commissioner, Denver,
                  Validity of Tribal Customary Adoptions, at 3-4 (March 30, 2005) [hereinafter "Validity of Tribal Customary Adoptions". We concluded that there was not sufficient evidence to find K~'s adoption valid
                  pursuant to the CFPC, given the lack of consent to the adoption by K~'s biological
                  father and the lack of a homestudy on the petition and report on the child. No further
                  information was provided which would affect our conclusion in this regard. Thus, the
                  question presented is whether the adoption was valid as a customary adoption given
                  the submission of the enacted Customary Adoption Code (hereinafter "the enacted Code").
               
               Though a "customary adoption" typically involves less formal proceedings, at the time
                  of our March 2005 opinion, the Tribe indicated that it had codified its procedures
                  for tribal customary adoptions. See Validity of Tribal Customary Adoptions. Analysis of the code then provided by the Tribe indicated that K~'s adoption would
                  have been considered a valid customary adoption but for the lack of a certification
                  provision enacting the code. It appears from the submission of the enacted Code in
                  conjunction with the request for reconsideration in this matter, that the code reviewed
                  previously was only a draft version. Careful comparison of the provisions of the draft
                  previously reviewed with the provisions of the final, enacted Code revealed some changes,
                  but none that would affect our conclusions regarding the validity of K~'s adoption
                  by the NH and his spouse. The enacted Code, however, was certified as of May XX, 2005,
                  and K~'s adoption occurred November XX, 2003. Thus, a question arises as to whether
                  the enacted Code can be applied retroactively to K~'s adoption.
               
               Under principles of statutory interpretation, legislation is usually prospective unless
                  it states with specificity that retroactive or retrospective application will apply.
                  As the Supreme Court has explained, "[r]etroactivity is not favored in the law. Thus,
                  congressional enactments and administrative rules will not be construed to have retroactive
                  effect unless their language requires this result." Bowen v. Georgetown Univ. Hosp., 488 U.S. 204, 208 (1988) (citing Greene v. U.S., 376 U.S. 149, 160 (1964) ('first rule' of statutory construction is that "legislation must be
                  considered as addressed to the future, not to the past") (internal citation omitted))
                  (other citations omitted).
               
               However, the Supreme Court has recognized that Indian tribal law is peculiar in both
                  its sovereign promulgation and its reflection of the customs of Indian tribes, and
                  thus that it generally is not subject to standard legal interpretations. In a case
                  in which the question of implied remedies under the Indian Civil Rights Act (ICRA)
                  - which imposes restrictions upon tribal governments similar to the guarantees incorporated
                  in the Federal Bill of Rights - was evaluated (and rejected), the Court stated that
                  resolution of statutory issues arising under the ICRA "will frequently depend on questions
                  of tribal tradition and custom which tribal forums may be in a better position to
                  evaluate than federal courts. … [w]e have … recognized that the tribes remain quasi-sovereign
                  nations which, by government structure, culture, and source of sovereignty are in
                  may ways foreign to the constitutional institutions of the Federal and State governments."
                  Santa Clara Pueblo v. Martinez, 436 U.S. 49, 56 (1978). The Court emphasized the importance of the federal judiciary
                  not interfering with a tribe's ability to "maintain itself as a culturally and politically
                  distinct entity" absent clear congressional authority. Id. This notion was earlier recognized by the Eighth Circuit when it affirmed that tribal
                  customs and usages generally inform Indian law, especially in matters of domestic
                  relations. See, e.g., Halowell v. Commons, 210 F. 793 (8th Cir. 1914) (finding heir from polygamous marriage lawful because
                  polygamy was in accordance with customs and usages of the tribe). Thus, the standard
                  principles of statutory construction are not necessarily of consequence in evaluating
                  the application of tribal laws.
               
               Further, the Eighth Circuit has recognized the inherent authority of tribal courts
                  with respect to matters over which Congress has not explicitly exercised power. See Conroy v. Conroy, 575 F.2d 175, 178 (8th Cir. 1978) ("[t]his Court lacks any general power to review
                  and oversee the Tribal Courts in their resolution of questions concerning the authority
                  and power of Tribal Courts." (citation omitted). And, domestic relations are such
                  matters squarely within the purview of tribal courts' authority. See id. at 181-82 ("Among those powers retained, the power of a tribe to regulate the domestic
                  relations of its members, historically well established, remains undisturbed."). As
                  we previously noted, the Indian Child Welfare Act of 1978 (ICWA), 25 U.S.C. § 1902,
                  et seq., gives Indian tribes exclusive jurisdiction over child custody proceedings and adoptions
                  involving an Indian child, such as K~, who resides on or is domiciled within the reservation
                  of the tribe. See 25 U.S.C. § 1911(a), accord Mississippi Band of Choctaw Indians v. Holyfield, 490 U.S. 30, 36 (1989); Sayers v. Beltrami County, 481 N.W.2d 547, 550 (Minn. 1992). Thus, the real question before us is whether the
                  White Earth Tribal Court would find that the enacted Code applies retroactively to
                  K~'s adoption.
               
               Tribal customary law, because it necessarily reflects long-standing principles and
                  practices embraced by a tribe, i.e., customs, can be seen as formally stating or clarifying
                  existing codes of behavior within the tribe, rather than as setting forth entirely
                  new standards. See Barnett v. Prairie Oil & Gas Co., 19 F.2d 504, 506 (8th Cir. 1927) (regarding long-established tribal customs as tribal
                  'common law'). While enacted tribal laws may solemnize certain practices in domestic
                  relations, they do not impliedly render practices performed without such solemnization
                  invalid. See id., citing Carney v. Chapman, 247 U.S. 102 (1918) (declining to construe Chickasaw tribal marriage statute "as
                  purporting to invalidate marriages not so solemnized"); cf. C~, 575 F.2d at 182 (reviewing tribal code whose specific terms decreed that "Indian
                  custom marriage and divorce consummated after" a date certain "shall not be recognized.").
               
               In this case, while the enacted Code renders "customary adoption" a statutory construct,
                  it clearly acknowledges that this legal process is one which is rooted in and reflects
                  the past practices of the tribe, defining "customary adoption" as "a traditional tribal
                  practice recognized by the community and tribe." See Customary Adoption Code, tit. 4a-1 § C.7. The enacted Code states that the Customary
                  Adoption Code reflects a policy of preserving the tribe's culture, values, clan system,
                  and relationships, id. at § B.3, and that the Code is to be "liberally interpreted and construed as an exercise
                  of the inherent sovereign authority of the [tribe] ... [t]o embody and promote the
                  basic traditional values of the [tribe] … regarding the protection and care of the
                  tribe's children." Id. at C.1. It is clear from this language that the enacted Code is indeed of the type
                  that reflects and solemnizes a long-established practice rather than setting forth
                  a new procedure. See Customary Adoption Code, tit. 4a-12.1 (allowing that a customary adoption which is
                  "conducted in a manner that is a long-established, continued, reasonable process and
                  considered by the people of the White Earth Band to be binding and authentic … may
                  be certified … as having the same effect as an adoption order issued by this court").
                  Thus, we conclude that the White Earth Tribal Court would find that the enacted Code
                  applies retroactively in a case such as K~'s, where the adoption otherwise satisfies
                  the terms of the enacted Code. Therefore, the enacted Code may be considered to be
                  effective retroactively, rendering K~'s adoption by J~ and his spouse valid from its
                  inception.
               
               CONCLUSION
               For the foregoing reasons, we conclude that the customary adoption of K~ was valid
                  under the Tribe's adoption laws, pursuant to the Tribe's Customary Adoption Code.
                  Therefore, there is sufficient evidence to establish that K~ is the NH's legally adopted
                  child for purposes of payment of CIB.