(a) A person does not commit a crime under this article if:
(1) He was a peace officer engaged in the lawful performance of his duties; or
(2) He was an officer, employee or agent of a communication common carrier who, while acting in the normal course of his employment, and while engaged in any activity which was a necessary incident to the rendition of his service or to the protection of the rights or property of the carrier of such communication, intercepted, disclosed or used a communication transmitted through the facilities of that carrier; or
(3) He relies in good faith on a lawful court order or legislative authorization.
(b) The burden of injecting the issue under subsection (a) is on the defendant, but this does not shift the burden of proof.