How long should a warning last?
[ch 6: pages 71-72]The Acas Guide suggests that a first written warning will be disregarded for disciplinary purposes after a set period, such as six months. It says that a final warning should also normally remain current for a set period, such as 12 months, and contain a statement that further misconduct or unsatisfactory performance may lead to dismissal.
When calculating the duration of a warning, the day the warning is issued should be counted:
Mr Malin was given a final written warning in a letter dated 29th January 1992 which stated that it lasted “for a period of 12 months from the date of this letter”. In a decision confirmed by the EAT, the employment tribunal held that the warning expired at midnight on 28th January 1993. It was therefore unfair to rely on the final warning to justify his dismissal in relation to an incident concerning the manner in which he answered the telephone to a manager that occurred on 29th January 1993, the day after the warning expired.
Bevan Ashford v Malin [1994] UKEAT 43_94_2012
Although the employer should put a time limit on a warning so that it expires after a certain period of time, if it does not do this, there is no assumption that it will have lapsed after a certain amount of time has passed (Kraft Foods Ltd v Fox 1978 ICR 311). (See also “Lapsed warnings” below.)