Texas courts apply the "eight corners" rule to determine whether an insurer has the duty to defend an insured, comparing the plaintiff's pleading allegations to the insurance contract provisions without regard to the facts that develop during discovery and trial. See National Union Fire Ins. Co. v. Merchants Fast Motor Lines, Inc., 939 S.W.2d 139, 141 (Tex. 1997). Unlike the duty to indemnify, the duty to defend arises when the plaintiff alleges facts that potentially support claims for which there is coverage. Id. An insurer's duty to defend an insured is determined under the "eight corners" rule. That is, an insurer's duty to defend is determined by looking at the factual allegations in the underlying pleading and the language of the insurance policy. Id. If the petition does not allege facts within the scope of coverage, the insurer is not required to defend the suit. Id. In applying this rule, we give the pleadings a liberal interpretation. Id. The duty to defend is determined from the face of the pleading, without regard to the ultimate truth or falsity of the allegations. Argonaut Southwest Ins. Co. v. Maupin, 500 S.W.2d 633, 635 (Tex. 1973). Under the "complaint allegation rule," factual allegations in the pleadings and the policy language determine an insurer's duty to defend. American Physicians Ins. Exch. v. Garcia, 876 S.W.2d 842, 847-48 (Tex. 1994). "If a petition does not allege facts within the scope of coverage, an insurer is not legally required to defend a suit against its insured." Id. at 848. Texas courts sometimes refer to the "complaint allegation" rule as the "eight corners" rule. See National Union Fire Ins. Co., 939 S.W.2d at 141. When we apply this rule, we give a liberal interpretation to the allegations of the petition. Id. We "focus on the factual allegations that show the origin of the damages rather than on the legal theories alleged." Id. (quoting lower court's decision, 919 S.W.2d 903, 905 (Tex. App.--Eastland 1996)).