Jurisdiction — In general — Territorial — Exemptions from and restrictions upon territorial jurisdiction — Foreign States — Oil spill — Foreign State-owned corporation — Sovereign immunity — Foreign Sovereign Immunities Act 1976 — Commercial activity exception — Relevance of contractual relationship in determining whether activity commercial — Whether act of drilling uniquely sovereign — Non-commercial tort exception to grant of immunity — Purpose — Whether tort as a whole occurred within United States — Whether acts discriminatory in nature — The law of the United States