California cases which have upheld decisions by trial courts to apportion between defendants liability for attorney's fees awards. (See cases collected in Pearl, supra, 3.12, pp. 3-10 to 3-12, cf. Feminist Women's Health Center v. Blythe (1995) 32 Cal. App. 4th 1641, 1672 39 Cal. Rptr. 2d 189 no error in failing to apportion without request in the trial court). The theory backing an apportionment under Code of Civil Procedure section 1021.5 is importation of earlier federal law precedents. Washburn v. City of Berkeley (1987) 195 Cal. App. 3d 578, 592 240 Cal. Rptr. 784 asserts: "Neither party cites a California case in which the court has calculated a fee award as did the trial court in this case. Federal courts have adopted various methods of apportioning or allocating fees among defendants in cases involving fee awards pursuant to 42 United States Code section 1988, and this court may look to federal law in applying Code of Civil Procedure section 1021.5. In Grendel's Den, Inc. v. Larkin (1st Cir. 1984) 749 F.2d 945 the court instructed, 'A number of theories for apportioning fees have been advanced . . . . Among them are the simplest approach of dividing the award equally among the defendants . . ., and the more sophisticated approaches of apportionment by degree of each defendant's liability . . ., and apportionment by relative time spent litigating against each defendant. . . . Each of these theories may be more or less valid in a given case.' ( Id., at pp. 959-960)". At the outset we note that there are two aspects of such an "apportionment." One is liability between the different opposing parties and the successful party. The other is responsibility for contribution or indemnity between opposing parties. As to the first aspect, we disavow the notion that, as a general matter, opposing parties are entitled to an apportionment of their liability under Code of Civil Procedure section 1021.5 as to the successful party. An award of attorney's fees under Code of Civil Procedure section 1021.5 is an obligation. When an obligation is imposed on several persons it is presumed to be joint. ( 1431). Treating the Code of Civil Procedure section 1021.5 obligation of more than one opposing parties as joint is consistent with the purposes of that statute. If the obligation is apportioned in the sense that it is not joint the successful party faces greater difficulty in collection of the judgment for attorney's fees and some of the attorney's fees will not be recoverable if any opposing party is insolvent.