Thanks, smollie. In that case, or if supoenaed (sp?), I think I would feel obliged to try and only use the evidence that was being presented in court as, I believe, jurors are supposed to do. A properly run case should, surely, have all the evidence. Yeah, I know things go wrong sometimes.
But we don't have the death penalty in this country, so the situation wouldn't arise here.
If I was utterly convinced of my friends' innocence, the right thing to do in my view, even if subpoenaed, would be to keep schtum and go to prison for it.
I don't think I could lie deliberately in court, but I might if I thought the police were lying (has been known).
BTW, what do atheists swear on? Is it necessary to swear on anything? If you promise to tell the truth, you've promised.