Old King Coal
Although not a lawyer, as I understand the law ...
- Slander is a false statement
- Libel is a false and malicious statement
Libel can be caused by a written or spoken statement.
Given the circumstances reported here (they may not be accurate), I think the latter would likely apply.
Neither are offences, since they are not criminal, but civil actions.
BJCC
The policeman may have made the decision to test the pilot, but he was applying the criminal law, not the civil law.
The pax who allegedly made the accusation can still be held to account for his/her actions in the civil courts, although a pyrrhic victory may be the result.
We shouldn't forget that both codes run in parallel under some circumstances.