We are often asked the following when an investigation is being undertaken into an allegation of misconduct. Firstly, how much investigation should there be and, secondly, what do we do when it's one person's word against another? The case of Salford Royal NHS Foundation Trust v Roldan sets out some interesting comments on these often tricky issues.

Ms Roldan, a nurse from the Philippines, was alleged to have abused a patient in a number of ways (cleaning wipes thrown on the face, hand-slapping, v-signs, foot tapping with a saturation probe … the usual!). A senior manager interviewed Roldan and a colleague (Ms Denton) who claimed to have witnessed the events. Bang to rights you may say - the disciplinary panel agreed. They found Roldan's evidence unconvincing and preferred that of Denton; a classic case of believing one person's word over another's. They dismissed Roldan prompting an unfair dismissal claim. However, the consequences for Roldan were much more serious than just losing her job as the matter was reported to the police and she also lost her right to remain in the UK.

The tribunal was concerned that, because the investigating manager and the disciplinary panel believed Denton had no reason to lie, they had not taken proper steps to look into the reliability of her evidence. For example, Denton was a new recruit whereas Roldan had been at the hospital for 4 years and had a long and unblemished record. Denton stated that Roldan had looked through a window to see if she was being observed, whereas the investigating manager admitted at the tribunal hearing that it would not have been possible to look through the window as the blinds would, in all likelihood, have been closed - not a budding Sherlock Holmes then! The tribunal also noted that no other employees had been questioned about Roldan's interactions with the patient. The tribunal found the dismissal unfair.

The case made its way to the Court of Appeal which agreed with the finding of unfair dismissal. They stated that, when assessing the reasonableness of an investigation, tribunals should take into account the gravity of the consequences for the employee; where these are serious, the investigator must be "even-handed" in looking for evidence in the accused's favour as well as evidence against them.

The court also commented that an employer faced with a conflict of evidence does not always have to decide that it "believes" one person and not another. It could decide that the difference is merely one of perception, and that both parties are telling the truth as they see it. Alternatively, it could decide that the conflict cannot be resolved, in which case the accused employee must have the benefit of the doubt.

In summary, the more severe the consequences of the disciplinary the greater the obligation on you to conduct a thorough investigation; in particular to scrutinise any evidence uncovered by a disciplinary investigation properly - elementary my dear Watson. Also, when faced with one employee's word over another, you are not obliged to believe one and not the other. If there is a reasonable degree of doubt over which version to believe then the 'accused' should be given the benefit of the doubt. The same principal applies in grievance processes. If there is a conflict of evidence that cannot be resolved then it should be reasonable to find that the complainant has not made out their complaint but this does not mean that they have lied.