Most people are very familiar with the concept of warnings given to employees for disciplinary or performance related issues. It is an established employment law principle that, except in very serious cases, an individual should usually be given a series of warnings about his/her conduct or under-performance with reasonable opportunities to correct matters before the employer should consider dismissal. Usually, the employee will be told that the warning will remain ‘live’ for a certain period (say 6 or 12 months) so that if there are any further problems during that time, the employer will also be able to take into account the earlier matter in deciding which sanction is appropriate.

But what if the previous warning has expired? Can the employer still take the earlier problem into account or must the individual be treated as having a ‘clean slate’ when another disciplinary or performance related issue arises?

In 2006 this issue was first considered in the case of Diosynth Limited v Thomson. Mr. Thomson worked for a company which handled dangerous chemicals, and had received a written warning for a health & safety failure which his employers stated would remain on file for 12 months. An explosion on site occurred 16 months after the warning had expired, and Mr. Thomson was one of 18 employees whose health & safety failures were found to have led to the explosion. Mr. Thomson was dismissed but the other employees (who had no previous warnings) kept their jobs. The Court held that the expired warning could not be relied upon and ultimately found his dismissal to be unfair.

However, the question of expired warnings has since been re-examined in Airbus UK Limited v Webb. Mr. Webb had received a final written warning from his employers which was to remain on file for 12 months. After the 12 month period had finished, Mr. Webb was involved with 4 other employees in an incident which was found to be serious misconduct. Mr. Webb was dismissed, but the other 4 employees were not as they had no previous disciplinary record. Ultimately, the Court found the dismissal to be fair as Mr. Webb’s expired final warning had not been the main reason for him losing his job.

Where do these cases leave employers?  The initial Diosynth decision suggested that expired warnings had to be ignored for all purposes when employers were considering which sanction to impose for a ‘further offence’. Thankfully, the Airbus decision has since provided some welcome relief for employers. While it will still be unfair for an employer to rely upon an expired warning as the main reason for a dismissal, this does not mean that the employer cannot take the expired warning into account (where it is appropriate to do so) so long as the expired warning itself is not the main reason for dismissal.

This probably offers some balance between not unfairly penalising an individual because of something which happened in the distant past, and the right for an employer to take into account relevant past problems which might otherwise be artificially disregarded. However, there may be a very fine distinction in some cases between whether an expired warning has only been a contributing factor in the employer’s decision or has actually been the main reason for sanction.