and unreasonable as to amount to a clear and prejudicial error of law. Walker v. Packer, 827 S.W.2d 833, 839 (Tex.1992) (orig. proceeding). With respect to the resolution of factual issues or matters committed to the trial court’s discretion, we may not substitute our judgment for that of the trial court unless the relator establishes that the trial court could reasonably have reached only one decision and that the trial court’s decision is arbitrary and unreasonable. Id. at 839-40. This burden is a heavy one. In re CSX Corp., 124 S.W.3d 149, 152 (Tex.2003) (orig. proceeding). We give deference to a trial court’s factual determinations, but we review the trial court’s legal determinations de novo. In re Labatt Food Serv., L.P., 279 S.W.3d 640, 643 (Te ntonio 2004, orig. proceeding) (<HOLDING>). The Trial Court Abused its Discretion by
holding that mandamus was appropriate remedy because temporary order granting visitation is not appealable holding that party may challenge revocation of certificate by filing either mandamus petition or other appropriate action in trial court holding that mandamus is an appropriate remedy because the trial courts issuance of temporary orders is not subject to interlocutory appeal holding that mandamus is appropriate to challenge temporary orders holding that mandamus is appropriate remedy because temporary order granting visitation is not appealable