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,
Wash. L. & Rev.
Available at: https://digitalcommons.law.uw.edu/wlr/vol38/iss2/15