We were considering a taxonomy of witnesses, seeing that there's 'material'
witness in some legalese but not in others. Then there's 'expert witness'.
Grice was one: he was called for 'conceptual analysis'. The proceedings
would be interrupted, and someone would say, "We need an expert witness
here". The implicature: a philosopher into conceptual analysis who would help
"in the interests of justice" to find out what the case is all about!