The Dallas Court of Appeals recently weighed in (again?) on whether a trial court’s erroneous ruling regarding designation of a responsible third party is subject to mandamus.  In this case, the trial court denied relator’s motion to designate a responsible third party.  The trial court did not allow relator to replead.  A divided panel held that it was an abuse of discretion to deny a motion to designate a responsible third party without allowing movant the opportunity to replead.  The court then addressed whether relator had an adequate remedy by appeal.  Citing its prior opinion in In re Oncor, the court held that "appeal is ordinarily an inadequate remedy when a trial judge erroneously denies a motion for leave to designate a responsible third party."  In a footnote, the court highlighted the split of authority regarding whether an appeal is an adequate remedy for a trial court’s erroneous ruling on a responsible third party issue.  In dissent, Justice Murphy argued that relator should have requested permission to replead, and, by failing to do so, waived error.  The court’s opinion in In re Houston M. Smith can be found here and the dissent here.