Does the duty not to return people to danger apply before they reach your shore?
Whether the duty not to return people to danger reaches the high seas: the Hirsi and Sale split.
What worked, what failed, what is reusable.
The contrast is the lesson. Hirsi Jamaa (Strasbourg) and Sale (US Supreme Court) asked the same question and answered it in opposite directions.
Hirsi: control, not territory. Italy violated the Convention by intercepting people at sea and returning them to Libya. Jurisdiction follows effective control: a state that exercises control on the high seas carries its obligations with it. The case paired Article 3 with Article 4 of Protocol 4, so the collective nature of the expulsion did real work.
Sale: the adverse anchor. The US Supreme Court read non-refoulement as not binding on the high seas, leaving interdiction lawful in US law. Treat it as the case to distinguish, not the one to avoid.
What failed. Arguments that lean on territorial presence concede the ground the state most wants to hold.
Reusable kit: lead with extraterritorial-jurisdiction-as-control (Hirsi), pair the non-refoulement claim with a collective-expulsion claim, and document the absence of any individual assessment.
Research resource, not legal advice. Read the original source before acting. Cases and campaigns are gathered by shared issue tags; some may be machine-extracted and pending human review.