Whether a federal court may disregard the prejudice resulting from Stromberg error and instead ask only what a hypothetical jury instructed on a valid, narrower theory would have found

QUESTION PRESENTED (Capital Case) A panel of the Ninth Circuit Court of Appeals held petitioner Joseph Smith’s capital sentencing jury was instructed in violation of Stromberg v. California, 283 U.S. 359 (1931), because one of the two alternative theories supporting the single aggravating factor in his case was invalid. But instead of determining the effect of the alternative-theory error on the actual sentencing jury’s verdict, see Brecht v. Abrahamson, 507 U.S. 619, 627 (1993), the panel ignored the error and applied a Ninth Circuit test that simply asked whether a hypothetical jury would have found the aggravating factor were it properly instructed on the valid, narrower theory only. The question presented is: In applying harmless error review under Brecht, may a federal court disregard the prejudice resulting from Stromberg error, i.e., the jury’s consideration of an invalid theory of liability, and instead ask only what a hypothetical jury instructed on a valid, narrower theory would have found? ii