In determining whether the Foreign State's activities are commercial, the FSIA requires that courts look to the nature of the act itself, rather than the purpose for which the foreign sovereign engaged in the act.
In 2015, the Supreme Court unanimously held in OBB Personenverkehr AG v. Sachs that the purchase of a rail ticket from an authorized agent in the US does not fall within the commercial activity exception when the lawsuit concerns a rail accident in a foreign country.