Nonparty appellate standing has been a surprising hot-button issue over the last year. In February the legal community, if not the nation as a whole, paid attention as the Ninth Circuit determined whether proponents of a California ballot measure (Proposition 8) had standing to defend that measure on appeal even when the state itself declined to do so. See Perry v. Brown, 671 F.3d 1052, 1064 (9th Cir. 2012); see also Perry v. Brown, 52 Cal. 4th 1116 (2011). But just after Perry a little-noticed unpublished Ninth Circuit memorandum disposition also explored the issue of nonparty standing to appeal: Newkirk v. Conagra Foods, Inc., No. 10-35667, 2012 WL 3836100 (Aug. 30, 2012).

In Newkirk the plaintiff sued Conagra Foods claiming that he developed a rare lung disease supposedly caused by his eating approximately six bags of popcorn every day for 11 years. Newkirk v. Conagra Foods, Inc., 727 F. Supp. 2d 1006, 1010 (E.D. Wash. 2010). Plaintiff hired an expert witness, Dr. David Egilman, to submit affidavits to support the theory that microwave popcorn emitted vapors that caused Newkirk's condition. See id. at 1013; see also Newkirk, No. 10-35643, 438 F. App'x 607, 608 (9th Cir. June 17, 2011).

Applying the expert testimony standards outlined in Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993), the district court summarily dismissed the case, finding that Newkirk failed to establish that the proffered expert testimony met the essential Daubert factor of scientific reliability. Newkirk appealed-but more unusually, so did Dr. Egilman.

Thus Newkirk raised the interesting issue of when a nonparty such as Dr. Egilman may appeal a ruling. The general rule is that only aggrieved parties may appeal. Dr. Egilman argued that he was aggrieved, and thus had standing to appeal, because the district court's order harmed his reputation and defamed him. The Ninth Circuit explained that nonparty standing is allowed only when (1) the appellant, though not a party, participated in the district court proceedings, and (2) the equities of the case weigh in favor of hearing the appeal. The court then dismissed Dr. Egilman's appeal because his mere filing of his expert reports in the litigation was not sufficiently participatory to confer nonparty standing.

Nevertheless, in reaching that conclusion the court highlighted that Dr. Egilman did not file papers objecting to the order below, nor did he argue the legal merits of the motion to exclude his expert testimony. In other words, the court implied that if Egilman, even as a nonparty to the litigation, had made his case below, he might have earned standing to appeal.

Our research has not uncovered a single precedent, state or federal, holding that an expert witness has standing to appeal. Although the court dismissed Dr. Egilman's appeal, it may have opened a door to such appeals so long as expert witnesses whose testimony is excluded object to such exclusion at the district court level.