Does the Attorney General have the burden of prejudice against a defendant in a civil case arising from an error in a search warrant application?

Defendant argues the error interfered with his constitutional right to the effective assistance of counsel by forcing "defense counsel to proceed to trial unprepared," and "wholly prevent[ing] [him] from developing evidence crucial to his defense, namely that the officers had lied about what they had seen and/or planted evidence to establish probable cause to search the van or to cover up the use of excessive force to detain" him. Defendant argues that prejudice should be presumed or assessed under the standard of Chapman v. California (1967) 386 U.S. 18, 24 [87 S.Ct. 824], i.e., the Attorney General would have the burden of proving beyond a reasonable doubt that the error did not contribute to the verdict. The Attorney General argues the error was one of state law only, to be evaluated pursuant to People v. Watson (1956) 46 Cal.2d 818, 836, i.e.,

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