In a lawsuit over conspiracy and malicious prosecution, a Cook County circuit judge honored a joint defense doctrine that rendered the information discussed between two defendants as privileged. The problem, however, is that no such doctrine formally existed in Illinois until now.The 1st District Appellate Court on Thursday acknowledged, to its own surprise, that there was no doctrine in this state, even though the federal courts believed it did exist.So, the justices went about establishing it in a 44-page ruling on a …