The question of whether a final written warning given in bad faith can be relied on by an employer in a subsequent dismissal for unrelated misconduct was considered by the Court of Appeal in the case of Way v Spectrum Property Care Ltd (22 April 2015).
In cases involving cumulative warnings a tribunal normally limits its enquiries to considering whether the final warning was something that a reasonable employer could reasonably take into account when deciding whether to dismiss the employee for subsequent misconduct. However, a tribunal could re-open the circumstances of a previous warning if:
(a) the warning was issued in bad faith
(b) there were no plausible grounds for issuing a final warning
(c) there is real concern that the warning was manifestly inappropriate.