Legal Requirements to Carry ID: Country-by-Country Variation

Whether adults must carry identification depends entirely on jurisdiction. No universal rule exists.

No General Obligation

United States: No federal law requires carrying ID. Hiibel v. Nevada (2004) allows states to require ID during lawful stops (24 states have "stop and identify" statutes). Driving requires license. Non-drivers: no obligation.
United Kingdom: No requirement. Police may ask for details; refusal isn't an offense unless driving.

Mandatory Carry

Germany: Ausweispflicht (§1 PAuswG). Germans 16+ must possess valid ID card (Personalausweis) or passport. Not required to carry constantly, but must produce on demand. Fine up to €3,000.
France: Contrôle d'identité allows police to demand ID. Foreigners must carry passport/residence permit.
Spain: Documento Nacional de Identidad (DNI) mandatory for citizens 14+. Foreigners: passport/TIE.
Japan: Foreign residents must carry residence card (zairyu card) always. Citizens: no national ID system.

Practical Advice

Research local laws before travel. Carry passport photocopy + digital backup. Know rights during police encounters. Diplomatic missions issue guidance for their nationals.