Employers may defeat whistleblowing claims if they are able to show that the employee was not acting in good faith or did not reasonably believe in the truth of the information disclosed.

Although there is not an express requirement that the employee reasonably believes in the truth of the information disclosed when making a public interest disclosure to his or her employer, the employee must act in good faith to come within the protection of the legislation. Where evidence was adduced to the effect that there was no truth in the allegations, the tribunal was entitled to conclude that there was an absence of good faith. There was no need to consider expressly whether or not there had been an honest mistake. (Muchesa v Central & Cecil Housing Care Support, EAT)