The first definitive interpretation of "gross negligence" within the meaning of the 1957 amendment to the Host-Guest Statute has been given by the Washington court in the case of Crowley v. Barto.
Washington Case Law,
Torts—Gross Negligence Under the Guest Statute,
38 Wash. L. Rev.
Available at: https://digitalcommons.law.uw.edu/wlr/vol38/iss2/15