Lies protecting peers
Deceit to maintain client confidentiality
Deceptive professional practices
A lie is the simplest way to protect a secret, though some have worked out subtle forms of evasion in answering unauthorized questions regarding a professional secret, such as "I know nothing about it" (with the mental reservation "to communicate to others"). The line between appropriate and inappropriate requests for information may shift from one society to another and be revised over time; but wherever the line is drawn, those charged with secrets have to decide how best to protect them. The same loyalty also shields colleagues. Politicians, for example, or professionals may be reluctant to divulge the incompetence or dishonesty of their fellows. The problem arises when loyalty or professional ethics in the interests of peers and clients overrides law and morality itself.
A doctor may fail to disclose a pilot's unstable heart condition that may lose him his job.