The wife in In re Marriage of Plescia (1997) 59 Cal. App. 4th 252 [69 Cal. Rptr. 2d 120] argued that this elimination of the lack of diligence requirement implied a legislative elimination of the equitable defense of laches as well. This court disagreed, stating: "It is a fundamental tenet of statutory interpretation that absent any indication that the Legislature intends a statute to supplant common law, the courts should not give it that effect. Of course, this tenet will not apply when a Legislature has minutely described the limitations and exceptions dealing with a given subject matter. In the instant case [wife] urges us to supplant the well-established common law doctrine of laches through the elimination of a diligence requirement for a statute of limitations, an elimination that is only apparent after a close reading of several often modified statutes. While it appears to be true that the consideration of diligence has been eliminated when a court enforces a spousal support order by a writ of execution, this sleight of hand interpretation will not be expanded to areas of the common law long held established. Absent any legislative intention that laches has been supplanted as an equitable defense, we refuse to condone its supplantation by fiat. "It is also a fundamental tenet of statutory interpretation that legislation will be interpreted on the assumption that the Legislature was aware of existing judicial decisions. Although there has been very little California litigation on this specific issue, the existence of a laches defense to spousal support arrearages has long been recognized. In other states where this same issue has been considered, laches has been allowed as an equitable defense. Also, in at least 18 other states the defense of laches has been upheld in an action on spousal support arrearages. In addition, there are states that do recognize laches as a valid defense to spousal support, but simply have not had a case which met all of the requirements of laches. It is clear that the laches defense to spousal support is established in judicial opinions reflecting the common law. Assuming that the Legislature was aware of this established law, its failure to use the language of laches weighs in heavily against appellant's argument. "Moreover, one of the fundamental tools for statutory interpretation is the maxim expressio unius est exclusio alterius. This maxim is roughly translated as 'the expression of the one thing implies the exclusion of the other.' In the statutory scheme at hand, the Legislature eliminates from judicial consideration the requirement of diligence in a spousal support action. (See 291, 4502, 5101.) However, it has long been established that the requirements of a valid laches defense are: (1) unreasonable delay, and (2) undue prejudice to the party raising the defense. While diligence may be a factor taken into account when examining the reasonableness of a delay, these two doctrines are certainly not coterminous in definition. Further, diligence has very little to do with the prejudice aspect of the laches defense. Thus, when the Legislature expressly eliminated the diligence defense, it must be seen to have left all other defenses alone, especially since we have no indications to the contrary. "Taking into account the long common law history of the laches defense, and the large amount of judicial support for it in other states, we find the Legislature's failure to mention laches quite conspicuous. When the Legislature discontinued looking at diligence, it could have eliminated the laches defense as well. It did not do so. Thus, we conclude that the Legislature's decision to leave laches out of its legislative scheme allows that remedy to remain available in appropriate cases." (Plescia, supra, 59 Cal. App. 4th 252, 261-262.)