Whether or not behaviour constitutes gross misconduct is a difficult question. However, the answer is important as it will determine the action an employer can take. If the employer can show that, by his or her actions, an employee has “disregarded the essential conditions of the contract of service”, or, to put it another way, has completely undermined the employment relationship by a “deliberate flouting” of its most basic terms (Laws v London Chronicle (Indicator Newspapers Ltd)  2 ALL ER 285), the employer will be contractually entitled to bring the contract to an immediate end without notice or pay in lieu of notice.
However, just because a dismissal is lawful under the terms of the contract, it does not mean it will be “fair” under statute. A dismissal for misconduct (including gross misconduct) will only be fair if, at the time it took the decision to dismiss, the employer believed the employee to be guilty of the misconduct, had reasonable grounds for that belief and had carried out as much investigation as practicable (British Home Stores v Burchell  IRLR 379).
An employer should also be able to show that employees were aware of what type of behaviour might constitute gross misconduct. Examples of behaviour meriting dismissal will normally be set out in the disciplinary rules, although an offence that does not fall within the rules can still merit summary dismissal (The Distillers Company (Bottling Services) Limited v Gardner  IRLR 47).
Even when the disciplinary rules list the behaviour in question as meriting summary dismissal, this won’t be determinative of the issue. A Tribunal can go beyond the disciplinary rules to look at the conduct complained of and make its own decision. So, for example, in Sandwell & West Birmingham Hospital v Westwood UKEAT/0032/09 the employee’s breach of her employer’s policy (to call a doctor or senior nurse if a recalcitrant patient refuses to leave hospital premises after discharge) did not necessarily amount to gross misconduct simply because the employer’s disciplinary code stated that it would.
If the conduct can reasonably be categorised as gross misconduct, an employer cannot simply assume that dismissal will be justified. Before taking any decision to dismiss, the employer should look to see whether there are any mitigating factors which might make the decision unreasonable. Such factors may include length of exemplary service and the consequences of the dismissal for the employee (Brito-Babapulle v Ealing Hospital NHS Trust UKEAT/0358/12).
So, to be topical, an employer who watched England v Costa Rica on his widescreen TV and saw a “sick” employee amongst the spectators should not immediately assume that he can dismiss fairly just because the disciplinary rules say he can. Mitigating factors could be that the employee has 40 years’ unblemished service and he is Joe Hart’s dad.