road connecting Hyder to uninhabited mountain regions of British Columbia is equipped with neither American nor Canadian border controls, meaning that tourists from Canada proceeding northwards from Hyder are required to complete Canadian immigration formalities when they return to Stewart despite never having cleared American immigration. Historical Identification and freedom of internal movement have sometimes been instruments of oppression, for example in Canada's pass system, or Apartheid-era South Africa's Pass laws. Specific requirements The degree of strictness of border controls varies across countries and borders. In some countries, controls may be targeted at the traveller's religion, ethnicity, nationality, or other countries that have been visited. Others may need to be certain the traveller has paid the appropriate fees for their visas and has future travel planned out of the country. Yet others may concentrate on the contents of the traveller's baggage, and imported goods to ensure nothing is being carried that might bring a biosecurity risk into the country. Biometrics Several countries require all travellers, or all foreign travellers, to be fingerprinted on arrival and refuse admission to or arrest travellers who refuse to comply. In some countries, such as America, this may apply even to transit passengers proceeding to a third country. Many countries also require a photo be taken of people entering the country. America, which does not fully implement exit control formalities at its land frontiers (although long mandated by domestic legislation), intends to implement facial recognition for passengers departing from international airports to identify people who overstay their visa. Together with fingerprint and face recognition, iris scanning is one of three biometric identification technologies internationally standardised since 2006 by the International Civil Aviation Organization (ICAO) for use in e-passports and the United Arab Emirates conducts iris scanning on visitors who need to apply for a visa. The Department of Homeland Security has announced plans to greatly increase the biometric data it collects at American borders. In 2018, Singapore began trials of iris scanning at three land and maritime immigration checkpoints. Immigration stamps An immigration stamp is an inked impression in a passport or other travel document typically made by rubber stamp upon entering or exiting a territory. Depending on the jurisdiction, a stamp can serve different purposes. For example, in the United Kingdom, an immigration stamp in a passport includes the formal leave to enter granted to a person subject to entry control. In other countries,