D.C. Code § 47-335

Any revenue bonds, notes, or other obligations authorized by an act of the Council of the District of Columbia enacted subsequent to August 1, 1981, pursuant to § 1-204.90(a), may be secured by a mortgage of real property or a security interest in any revenues, assets, or other property, notwithstanding that such mortgage or other security interest may not have been authorized by such § 1-204.90(a) as of the effective date of such act.