Respondent Carol Sachs is a resident of California who purchased in the United States a Eurail pass for rail travel in Europe. She suffered traumatic personal injuries when she fell onto the tracks at the Innsbruck, Austria, train station while attempting to board a train operated by the Austrian state-owned railway. She sued the railway in Federal District Court, arguing that her suit was not barred by sovereign immunity because it is ‘based upon’ the railway’s sale of the pass to her in the United States.