Employers who discover misconduct in the workplace need to carry out an investigation before taking disciplinary action. In cases of gross misconduct, the investigation is particularly important. Nevertheless, a thorough investigation is important for the principles of natural justice and for general fairness.
Critically if an employer gets this stage wrong, like the foundations to any building this can cause problems later on if it is not rectified at the first opportunity in the disciplinary hearing. Employers in conduct cases have to demonstrate that they have conducted a reasonable investigation under the long established principles of BHS v Burchell . Failings in the investigation stage can render a case unfair and leave the employer open to a claim.
Smaller employers in particular can be daunted by not knowing where to start in the process. ACAS have published a guide to conducting workplace investigations which employers may find useful and you can read it here.