In Rutherford v. Babcock, 168 Ariz. 404, 814 P.2d 361 (App. 1991), the parties' marriage was dissolved in 1980, "the father's duty to support terminated on February 23, 1987," and the mother petitioned for enforcement on February 27, 1989. Id. at 405, 814 P.2d at 362. Former A.R.S. 12-2453, the child-support-enforcement statute in effect at the time, had been amended in 1983 to extend the time for enforcement from two years to three. See 1983 Ariz. Sess. Laws, ch. 263, 2. "The trial judge interpreted the phrase 'barred by pre-existing law' 12-505(B) to mean at the time the petition was filed, rather than at the time of the statutory amendment," and applied the two-year limitation. Id. at 406, 814 P.2d at 363. On appeal, the court explained this approach was incorrect and the relevant inquiry was whether the case was barred by the law existing before the amendment. Id. Because the mother in Rutherford had an enforceable right to collect arrearages at the time the statute was amended, the new statute of limitations applied. Id.