Dave is our client. There is no way around that. Anyway, the first thing we do is sort out to whom we owe attorney obligations.
Should seek witnesses: the extra homeless people outside the bar. We would be interested to know what they would say.
We would like to get the complaining witness to back out.
This kind of law is result-oriented. These cases arise because someone is trying to suppress evidence at trial. So the bias tends to be to try to find a reason to admit the evidence. That 5-volume set is full of decisions, most of which are permissive.