Ala. Code § 33-2-187

Docks facilities revenue bonds and refunding bonds and the income therefrom shall be exempt from all taxation in the state. Any of the docks facilities revenue bonds or refunding bonds may be used by the holder thereof as security for the deposit of any funds belonging to the state or to any instrumentality or agency of the state in any instance where security for such deposits may be required by law. Unless otherwise directed by the court having jurisdiction thereof, or by the document that is the source of power, a trustee, executor, administrator, guardian, or one acting in any other fiduciary capacity may, in addition to any other investment powers conferred by law and with the exercise of reasonable business prudence, invest fiduciary funds in any of the docks facilities revenue bonds or refunding bonds.