Arguing “abuse of discretion”

Trial courts rarely make rulings that are truly “irrational,” so when is an “abuse of discretion” actually an error of law or a lack of substantial evidence?

Jerry Clausen
2022 December

Abuse of discretion is among the more deferential standards of review, making it very difficult to overturn a discretionary ruling on appeal. As one appellate court famously stated, “An attorney who prosecutes an appeal from an order addressed to the trial court’s sound discretion is confronted with more than a daunting task. This is an uphill battle which, absent unusual circumstances, may be equated with Confederate General John Bell Hood’s attempt to capture ‘Little Round Top’ at the battle of Gettysburg in the Civil War. General Hood did not succeed.” (Estate of Gilkison (1998) 65 Cal.App.4th 1443, 1448.)

To make matters worse, formulations of the standard are often vague and unhelpful, making it difficult to identify, analyze, and argue abuse. Although varying in their precise wording, they generally consist of vague and indeterminate descriptions that boil down to the conclusion that the trial court has acted irrationally. (See, e.g., Shamblin v. Brattain (1988) 44 Cal.3d 474, 478 [“The appropriate test for abuse of discretion is whether the trial court exceeded the bounds of reason”]; People v. Jordan (1986) 42 Cal.3d 308, 316 [trial court abuses discretion when it acts “in an arbitrary, capricious or patently absurd manner”].) These formulations have often been criticized. (E.g., Hurtado v. Statewide Home Loan Co. (1985) 167 Cal.App.3d 1019, 1022 disapproved on other grounds in Shamblin, supra, 44 Cal.3d 474, 479, fn. 4 [standard is “so amorphous as to mean everything and nothing at the same time and be virtually useless as an analytical tool”]; People v. Jackson (2005) 128 Cal.App.4th 1009, 1019 [“abuse of discretion standard is itself much abused”].) But how does one argue that a trial court’s ruling was “irrational” – other than by simply declaring that “the trial court’s ruling was irrational”?

The truth is that (at least in my experience) trial courts rarely make rulings that are truly “irrational.” Not infrequently, however, they do draw erroneous conclusions of law or make findings of fact that are unsupported by substantial evidence. This article explains how, in many cases, a ruling may constitute an “abuse of discretion” not because it is irrational but because it is based on an erroneous legal conclusion or a finding that lacked substantial evidence – and how understanding this can provide the analytical tools to isolate and argue such an abuse of discretion on appeal.

Identifying the substantive-law boundaries of a discretionary ruling

In many cases, nebulous statements of the abuse of discretion standard of the sort recited above are coupled with language of limitation that begins to provide some clues to an analytical framework for evaluating the propriety of a discretionary ruling. Perhaps the most ubiquitous and most famous example is: “‘The discretion of a trial judge is not a whimsical, uncontrolled power, but a legal discretion, which is subject to the limitations of legal principles governing the subject of its action, and to reversal on appeal where no reasonable basis for the action is shown.’” (Westside Community for Independent Living, Inc. v. Obledo (1983) 33 Cal.3d 348, 355, italics added, cits. omitted; see 9 Witkin, Cal. Proc. (6th ed. 2022) Appeal, § 384, and cases cited therein.)

The court in City of Sacramento v. Drew (1989) 207 Cal.App.3d 1287 explained this limitation as follows, “The scope of discretion always resides in the particular law being applied, i.e., in the ‘legal principles governing the subject of (the) action....’ Action that transgresses the confines of the applicable principles of law is outside the scope of discretion and we call such action an ‘abuse’ of discretion. If the trial court is mistaken about the scope of its discretion, then the mistaken position may be ‘reasonable’, i.e., one as to which reasonable judges could differ. But if the trial court acts in accord with its mistaken view the action is nonetheless error; it is wrong on the law.” (Italics added.)

A couple of examples will help illuminate this concept. In Cooper v. Takeda Pharmaceuticals America, Inc. (2015) 239 Cal.App.4th 555, the plaintiff’s expert used a differential diagnosis (or “differential etiology”) to conclude that a drug used to treat the plaintiff’s diabetes caused him to develop bladder cancer. A differential etiology is a standard scientific technique for identifying the cause of a medical problem by first “ruling in” a list of potential causes of the problem and then, by process of elimination, “ruling out” those causes so as to reach a conclusion as to the most likely cause in a particular case. (Johnson & Johnson Talcum Powder Cases (2019) 37 Cal.App.5th 292, 308, fn. 6.) The expert in Cooper concluded that the diabetes drug was the “most substantial causative factor” of the plaintiff’s cancer. (Cooper, supra, at p. 570.) The trial judge struck this testimony, ruling that, although the expert purported to rule out a number of other potential causes, he did not have an adequate basis for excluding some of them. (Id. at p. 574.) In short, the trial judge excluded the expert’s opinion because the expert had failed to adequately rule out all of the other potential causes.

Substantive law

The appellate court reviewed this ruling for abuse of discretion. (Cooper, supra, 239 Cal.App.4th 555, 576.) It concluded the ruling conflicted with California’s substantive law of causation, which does not require a plaintiff to eliminate all other potential causes of an injury or illness in order to establish that one cause was the most probable. “Under the applicable substantial factor test,” the court said, “it is not necessary for a plaintiff to establish the negligence of the defendant as the proximate cause of injury with absolute certainty so as to exclude every other possible cause of a plaintiff’s illness, even if the expert’s opinion was reached by performance of a differential diagnosis.” (Cooper, supra, 239 Cal.App.4th 555, 578, original italics.) Accordingly, the court concluded, “[C]ases in which expert physicians perform a differential diagnosis to ‘rule in’ and ‘rule out’ other possible causes of a disease are not unique; the substantial factor rule of causation still applies in such cases. Thus, Dr. Smith was not required to rule out all other possible causes of bladder cancer before his testimony could be deemed admissible. The trial court’s ruling to the contrary contravened California law.” (Id. at p. 581, original italics.)

In short, because the applicable substantive law in Cooper did not require the plaintiff to exclude all potential causes of his cancer other than the diabetes drug, the trial court had no discretion to require that the plaintiff’s expert make a more stringent showing in order for his opinion to be admissible.

In City of Sacramento v. Drew, supra, 207 Cal.App.3d 1287, after a defendant successfully opposed the plaintiff city’s action to establish the validity of a special tax assessment district to raise unfunded costs for the construction of schools, the trial court refused to award the defendant attorney fees under Code of Civil Procedure section 1021.5. This section granted court’s discretion to award attorney fees to a successful party in any action resulting in the enforcement of an important right affecting the public interest if certain criteria were met – one such criterion being that “the necessity of private enforcement [is] such as to make the award appropriate.” The trial court in effect treated this requirement as one of causation, denying fees in part because it concluded that the district would “presumably” have been declared invalid even without the prevailing defendant’s participation in the lawsuit. (At p. 1292.)

Statutes can provide the governing legal principles

Where a statute is the source of the trial court’s discretion, the language and policy of the statute typically provide the “legal principles governing the subject of (the) action.” (Horsford v. Board of Trustees of California State University (2005) 132 Cal.App.4th 359, 393-394 [“judicial discretion must be measured against the general rules of law and, in the case of a statutory grant of discretion, against the specific law that grants the discretion”].) Thus, the City of Sacramento court looked to the language and legislative history of section 1021.5 and concluded that the trial court had misinterpreted the statute. The Court of Appeal agreed the section did contain a causal requirement – but the causal requirement was the one requiring that the action “resulted in the enforcement of an important right affecting the public interest.” (City of Sacramento, supra, 207 Cal.App.3d 1287, 1299.)

In contrast, the court said, the “[n]ecessity of private enforcement” requirement “‘looks to the adequacy of public enforcement.’” (Id. at pp. 1298-1299, cit. omitted.) “Thus, if there is a public attorney general available to enforce the important right at issue there is no utility in inducing a private attorney general to duplicate the function.” (City of Sacramento, supra, 207 Cal.App.3d 1287, 1299.) The court concluded that, as a practical matter, there was no public attorney general available to litigate the issue of the validity of the assessment. (Ibid.) The trial court’s ruling to the contrary was thus necessarily an abuse of discretion.

In the foregoing examples, the trial court errors were essentially legal errors. But because they were made in the context of a discretionary ruling, they were denominated an “abuse of discretion” rather than an “error of law.” (Horsford, supra, 132 Cal.4th 359, 393 [“Action that transgresses the confines of the applicable principles of law is outside the scope of discretion and we call such action an ‘abuse’ of discretion”].)

The role of substantial evidence review

In the course of making a discretionary decision the lower court may be required to make subsidiary factual findings. Where such a decision is based upon a finding not supported by substantial evidence, it is erroneous despite its discretionary nature. In such cases, the line between substantial evidence review and abuse of discretion review begins to blur, and opinions may vary as to the label (“substantial evidence” or “abuse of discretion”) that should apply. (E.g., compare Marriage of Terry (2000) 80 Cal.App.4th 921, 928-929 [in ruling on request for modification of spousal support, value and character of party’s separate estate and party’s support needs are fact issues subject to substantial evidence review] with id. at p. 936 (conc. opn. of Sepulveda, J.) [modification of spousal support is reviewed for abuse of discretion, “and such an abuse occurs when a court modifies a support order without substantial evidence of a material change of circumstances”].)

But regardless of the label, the analysis is functionally the same: “Review for substantial evidence applies to factual determinations; abuse of discretion applies when a lower court must delicately balance factual determinations to assess an uncertain future situation. But where … ‘the appellate court will be evaluating the factual basis for an exercise of discretion, there likely will be no practical difference in application of the two standards.’” (In re Caden C. (2021) 11 Cal.5th 614, 641, cits. omitted; see In re Robert L. (1993) 21 Cal.4th 1057, 1065 [“Sometimes it is difficult to distinguish between application of the sufficiency of the evidence standard and the abuse of discretion standard”].)

In a sense, the substantial evidence requirement imposes a boundary on the factual findings involved in a discretionary ruling in the same way that applicable legal principles impose a boundary on the legal conclusions involved in such a ruling. Thus, in some cases, it may be possible to attack the ruling by analyzing the quantity and quality of the evidence available to support it. It is true that both the substantial evidence standard and the abuse of discretion standard provide “considerable deference to the fact-finding tribunal” (Department of Parks & Recreation v. State Personnel Bd. (1991) 233 Cal.3d 813, 830-831); consequently, a substantial evidence attack on a discretionary ruling is likely to confer a smaller benefit than a legal attack on that ruling. But it nonetheless has the advantage of pinpointing the flaw in the lower court’s ruling and placing the analysis of that flaw on more familiar and thus more accessible terrain. In short, it is better than simply arguing that the ruling was irrational.


In addition to the two situations discussed above, an abuse of discretion may be found when the trial court is vested with discretion but fails to exercise it. This commonly occurs (1) where the record demonstrates the trial court erroneously believed it had no discretion (see, e.g., Riskin v. Downtown Los Angeles Property Owners Ass’n (2022) 76 Cal.5th 438, 448-449 [trial court erroneously concluded it lacked discretion to deny attorney fees]) and (2) where a trial court decides a discretionary matter by adhering to a standard practice or policy rather than by evaluating case-specific facts and circumstances (see, e.g., People v. Hernandez (2011) 51 Cal.4th 733, 743 [trial court erred in stationing bailiff behind defendant during latter’s testimony as a matter of standard policy instead of exercising discretion on case-specific basis to evaluate need for such heightened security and potential prejudice that might result]).

However, when the trial court has in fact exercised its discretion and its ruling is supported by substantial evidence and does not contravene the applicable law, absent unique circumstances, an appellant may want to think twice about taking an appeal that may prove as difficult and futile as General Bell’s assault on Little Round Top.

Jerry Clausen Jerry Clausen

Jerry Clausen is a plaintiff-side appellate lawyer specializing in tort, insurance, and employment law. He is an author of California Government Tort Liability Practice (CEB).

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