You point out clearly that staff must obey the law. That includes not tapping telephones, intercepting email or voicemail messages, et cetera. And then the next paragraph:
"As stated in the code, there may be extraordinary circumstances where exceptions to this rule (and others) can be justified in the public interest."
It's not your understanding, is it, that there is a public interest defence to tapping telephones, which under the relevant statute is an absolute offence, and there isn't a defence, for example, of acting in the public interest? Do you follow that?