[Thanks to Michael Reed Employment Legal Officer at the Free Representation Unit for preparing this case summary]
Only if it was issued in bad faith or manifestly inappropriate, says the Court of Appeal in Davies v Sandwell. Otherwise, past warnings should not be reconsidered.
Ms Davies was dismissed for misconduct. In making their decision, the Council considered a previous written warning. Ms Davies said that the warning was wrong; she had not committed the alleged misconduct. She argued the validity of the warning should be considered as part of her unfair dismissal claim.
The Court of Appeal disagreed. The tribunal's role was to consider the fairness of the dismissal. This included deciding whether it was reasonable to rely on a previous warning -- but that did not mean deciding whether the warning should have been issued. Only in the exceptional case of bad faith or a manifestly inappropriate warning should a tribunal conclude it was unreasonable to rely on it.
The Court of Appeal also called for robust case-managment. Noting that much of the evidence given over four weeks had been irrelevant, they said tribunals (and parties) should exclude irrelevant material and focus on the real issues, rather than wasting time and money.