Antelope Valley Groundwater Cases Antelope Valley-east Kern Water Agency v. L. A. Cnty. Waterworks Dist. No. 40, Cross, 30 Cal. App. 5th 602

BB&K served as AVEK’s general counsel from 1987 to Jan 2016 (Michael Riddell of BB&K was AVEK’s general counsel); starting in 2004 BB&K also began representing Los Angeles County Water District No. 40 (District No. 40) in the Antelope Valley Groundwater Adjudication (AVGA).
AVEK was not an original defendant in the AVGA; when AVEK later entered the litigation it retained separate counsel (Brunick) for the adjudication while retaining BB&K for unrelated matters.
From 2004–2015 BB&K concurrently represented District No. 40 in the AVGA and provided non-AVGA services to AVEK; AVEK, via separate counsel, advanced claims (e.g., return-flow rights, fee apportionment) that could conflict with District No. 40 yet did not object to BB&K’s dual role for more than a decade.
The court approved a global settlement and entered final judgment in December 2015 resolving disputes between AVEK and District No. 40.
In early 2016 AVEK terminated BB&K, then demanded BB&K stop representing District No. 40; seven months later AVEK moved to disqualify BB&K for concurrent/conflicting representation, alleging lack of an informed written waiver.
The trial court denied disqualification, finding (inter alia) implied/informed consent from AVEK and unreasonable, prejudicial delay; the appellate court affirmed.

Issue	Plaintiff's Argument (AVEK)	Defendant's Argument (District No. 40/BB&K)	Held
Whether concurrent representation without a written waiver requires automatic disqualification	Lack of a written informed consent per former Rule 3-310 mandates disqualification	Court may consider consent by conduct, delay, prejudice, and other equitable factors	Court affirmed denial: implied/informed consent by conduct can bar disqualification and is not defeated by absence of a writing
Whether AVEK’s long delay in moving to disqualify estops relief	Delay irrelevant if automatic disqualification rule applies	Delay is relevant; extreme delay causing prejudice can bar disqualification	Held delay (10+ years) was unreasonable and highly prejudicial; estoppel supports denial
Whether risk of misuse of confidential information required disqualification	Focus on per se rule; written waiver required to cure loyalty/confidentiality concerns	No evidence BB&K used or possessed AVEK confidences relevant to AVGA; concurrent AVGA representation had ended	Court found no proof of confidentiality breach risk; disqualification unnecessary
Standard of review and deference to trial court findings	AVEK contends application of per se rule was legal, not factual	Trial court factual findings (implied consent, prejudice) supported by substantial evidence	Abuse of discretion standard; trial court findings supported by substantial evidence — affirmed

Flatt v. Superior Court, 9 Cal.4th 275 (Cal. 1994) (distinguishes successive vs. simultaneous conflicts; simultaneous representation often triggers automatic disqualification)
People ex rel. Dept. of Corporations v. SpeeDee Oil Change Sys., Inc., 20 Cal.4th 1135 (Cal. 1999) (disqualification motions are equitable; courts may weigh delay, prejudice, and other equitable factors)
River West, Inc. v. Nickel, 188 Cal.App.3d 1297 (Cal. Ct. App. 1987) (unreasonable delay and prejudice can imply waiver or consent and bar disqualification)
State Farm Mut. Auto. Ins. Co. v. Federal Ins. Co., 72 Cal.App.4th 1422 (Cal. Ct. App. 1999) (rejects implied consent on facts; recognizes timeliness and knowledge are critical to implied-consent analysis)
Blue Water Sunset, LLC v. Markowitz, 192 Cal.App.4th 477 (Cal. Ct. App. 2011) (reiterates that simultaneous representation generally leads to automatic disqualification, but did not foreclose consideration of context)
Elliott v. McFarland Unified School Dist., 165 Cal.App.3d 562 (Cal. Ct. App. 1985) (implied consent may be found from conduct and agreements; written waiver is not always the only basis for consent)