Katelin Eunjoo Seo v. State of Indiana, 148 N.E.3d 952

Seo reported an alleged rape and told police her iPhone contained relevant communications; with her consent officers performed a forensic download and returned the device.
Investigation later focused on Seo for alleged stalking/harassment; police arrested her and seized a locked iPhone she refused to unlock.
Detective Inglis obtained a warrant to forensically search the phone and a second warrant that compelled Seo to unlock the phone under threat of contempt; Seo refused and was held in contempt by the trial court.
Seo appealed the contempt order; while the appeal was pending she pleaded guilty to one stalking count and other charges were dismissed, but the contempt order remained stayed.
The Indiana Supreme Court granted transfer and reversed the contempt finding, holding that forcing Seo to unlock her phone would violate the Fifth Amendment because the act is testimonial and the State failed to meet the foregone-conclusion exception.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Whether compelling Seo to unlock her iPhone violates the Fifth Amendment privilege against self-incrimination	Unlocking is a non-testimonial physical act; the State already knows Seo controls the phone/password (foregone conclusion)	Unlocking is testimonial because it communicates that she knows the password, that files exist, and that she possesses them; State would gain information it lacks	Reversed contempt. Compelled unlocking is testimonial; foregone-conclusion exception not shown, so Fifth Amendment protects Seo
Mootness / justiciability of the appeal	Case not moot: State still has investigatory interest and the contempt order remains a live threat	Case moot: plea agreement resolved underlying charges and civil contempt terminated	Majority: case presents a live dispute and is adjudicated. Dissent: case is moot and should not have been decided

Fisher v. United States, 425 U.S. 391 (established the act-of-production doctrine and the "foregone conclusion" test)
United States v. Hubbell, 530 U.S. 27 (limited application of foregone-conclusion exception; production can be testimonial)
United States v. Doe, 465 U.S. 605 (act of production can be testimonial when it implicitly admits existence/possession/authenticity)
Riley v. California, 573 U.S. 373 (smartphones implicate heightened privacy concerns)
Carpenter v. United States, 138 S. Ct. 2206 (Court cautious about extending established doctrines to digital-privacy contexts)
Estelle v. Smith, 451 U.S. 454 (State must gather evidence through its own labor, not by forcing testimony from the accused)
Hoffman v. United States, 341 U.S. 479 (Fifth Amendment protects against compelled testimonial links in the chain of evidence)
Couch v. United States, 409 U.S. 322 (privilege guards against compelled communications that would incriminate)
Pennsylvania v. Muniz, 496 U.S. 582 (testimonial requirement: communication must relate a factual assertion or disclose information)