Except as provided in § 7-1304.06 a, hearings shall be conducted in as informal a manner as may be consistent with orderly procedure. Persons who have been committed, or whose commitment is sought pursuant to § 7-1303.04 (b-1), have the right to be present during hearings and to testify, but shall not be compelled to testify, and shall be so advised by the Court. They shall have the right to call witnesses and present evidence, and to cross-examine opposing witnesses. The presence of the person may be waived only if the Court finds that the person has knowingly and voluntarily waived his or her right to be present, or if the Court determines that the person is unable to be present by virtue of his or her physical disability.
D.C. Code § 7-1304.06
Section 35 of D.C. Law 19-169 provided that no provision of the act shall impair any right or obligation existing under law.