As part of a disciplinary investigation, you will usually interview witnesses. During this process, you have every right to expect honesty. But suppose one of them lies in order to protect the employee under investigation: how should you deal with their actions and what effect do they have on the original proceedings?

What about the ACAS Code?

The ACAS Code of Practice on Disciplinary and Grievance Procedures is silent on the standards of conduct you can expect from witnesses. At first, this seems unhelpful, but it’s good news! The lack of detail means you have a wide discretion in how you deal with witnesses who are found to have lied during a disciplinary investigation. You can also rely on the implied duty of trust and confidence in the contract of employment. This dictates that an employee must always be truthful throughout the course of their employment. If not, you can use it as grounds for disciplinary action.

Impact on the hearing

Where you have discovered that an employee has lied, your first concern should be the impact it has on the original proceedings. Needless to say, their account and/or evidence must be completely disregarded in other words, you should only rely on other witness statements. If you don’t have any others, try to locate new witnesses.

Depending on the facts of the case, you may have to adjust a disciplinary sanction that has been imposed, as it could be unsafe.

Dealing with the witness

The next stage is to deal with the untruthful witness. Some form of disciplinary action should be taken against them. If not, other employees could conclude that there is no penalty for dishonesty. The sanction you impose should depend on the seriousness of the original matter under investigation; it must also come within the range of "reasonable responses".

Each case will turn on its own facts. For example, if the original employee was investigated for serious or gross misconduct, perhaps over an alleged theft or fraud, you could treat the witness’ actions similarly that is, they warrant summary dismissal. But if it occurred in connection with a minor matter, for example poor time-keeping a written warning may be more appropriate.

Ensure your disciplinary procedure states that employees "must not knowingly break any legal requirement in connection with their employment" in other words, the implied duty of trust and confidence. This allows you to take disciplinary action if they deliberately give a false or misleading statement.

When you write to a witness advising them that they will face a disciplinary hearing for providing a misleading or false statement, you must spell out the possible consequences. If dismissal is an option, always make this clear.