¶1This is an appeal by petitioner Pierre Ber-geron, guardian ad litem (GAL) of respondent Paula Moses, from an order dismissing his petition to have her committed to a facility for the mentally retarded. The trial judge dismissed the petition based on his finding that Moses was competent to refuse commitment. On appeal,
¶2I.
¶3In 1991, as Moses approached 21 years of age,
¶4II.
¶5We must first determine our standard of review of competency determinations *831under the Rights of the Mentally Retarded Citizens Act, D.C.Code §§ 6-1901 et seq. (1989). The Act presumes that individuals 14 year’s of age and older are competent to refuse commitment, id. § 6-1921, a presumption which is rebuttable only by proof beyond a reasonable doubt. Id § 6-1947. Thus, we will overturn a trial court’s determination of competency only where the evidence is such that, as a matter of law, a trier of fact would be compelled to find beyond a reasonable doubt that the individual was incompetent. Cf. Johnson v. Lloyd, 211 A.2d 764, 765 (D.C.1965) (upholding trial court’s finding of parental fitness and refusing “to rule, as a matter of law, in a situation where reasonable men may rightfully differ, that the trial court was in error”); Sullivan v. North Am. Accident Ins. Co., 150 A.2d 467, 470 (D.C.1959) (reversing trial court because plaintiffs evidence was virtually uncontroverted and overwhelmingly against judgment for defendant); Elliot v. Sears Roebuck & Co., 30 Conn.App. 664, 621 A.2d 1371, 1377 (1993) (holding that jury verdict should be set aside only where “jury could not reasonably and legally have reached its conclusion”). In this case, there was expert evidence on which the trial judge could have based a finding of incompetency, but he was not bound to credit this evidence and apparently did not do so. We cannot substitute our judgment for his.
¶6III.
¶7As to the remaining contentions, we find no merit to the GAL’s arguments. He submits that the trial judge misapprehended the standard for determining competency
¶8Nor do we find an abuse of discretion in the trial judge’s various evidentiary rulings. See Hannan v. United States, 76 U.S.App.D.C. 118, 120, 131 F.2d 441, 443 (1942) (holding that reception of evidence is matter of discretion). He correctly excluded evidence of Moses’ past behavior in the community and in particular placements as irrelevant to her present competence. Punch v. United States, 377 A.2d 1353, 1358 (D.C.1977), cert. denied, 435 U.S. 955, 98 S.Ct. 1586, 55 L.Ed.2d 806 (1978). The trial judge also properly exercised his discretion to exclude a third social worker’s testimony as well as testimony of an independent psychologist and his written report as cumulative evidence. Washington Times Co. v. Bonner, 66 App.D.C. 280, 290, 86 F.2d 836, 846 (1936). Finally, the trial judge did not err in denying expert status to the two social workers who testified. “The question whether an expert has been sufficiently qualified is ... ‘recognized as a matter for the trial judge’s discretion reviewable only for abuse. Reversals for abuse are rare.’” In re Melton, 597 A.2d 892, 897 (D.C.1991) (en banc) (citation omitted; emphasis added).
¶9Affirmed.
¶10. A guardian ad litem in mental retardation commitment proceedings has standing to appeal an order denying commitment. See D.C.Code § 6-1950 (1989); Super.Ct.Ment.Ret.R. 4(g).
¶11. At the time of the proceedings helow, Moses was already committed to the custody of the District of Columbia by way of the neglect system. D.C.Code §§ 6-2101 et seq. (1989 & Supp. 1994), 16-2301 et seq. (1989 & Supp.1994). Having since reached the age of 21, she is no longer in the District's custody but resides voluntarily in a District group home and participates in a sheltered workshop during the day.
¶12. Although, at the time of the hearing, the Act did not define "competent,” § 6-1922 (regarding the necessity of finding competence for voluntary admission) set forth basic considerations for determining competence: "the individual's understanding of what habilitation and care will be provided in the facility, and what alternative means of habilitation and care are available from community-based services.” Id. A recent amendment to the Act defines "competent” as “havfing] the mental capacity to appreciate the nature and implications of a decision to enter a facility, choose between or among alternatives presented, and communicate the choice in an unambiguous manner." 42 D.C.Reg. 721, 742 (Feb. 10, 1995). This new definition tracks the definition of “incapacitated individual” in the Health Care Decisions Act, D.C.Code § 21-2202(5) (1989).