[1] After the war's end its powers were continued and expanded by the Aliens Restriction (Amendment) Act 1919, allowing the government to continue using the 1914 Act from 1919 to 1920 and to investigate former enemy aliens "For the purpose of enforcing the provisions of" the forthcoming peace treaty.

Building on the restrictions of the Aliens Act 1905, the 1914 Act enabled the UK government to use Orders in Council rather than primary legislation to place restrictions on places foreigners (then legally known as aliens) could live, leave and arrive in the United Kingdom, to appoint officials to enforce them, to introduce a system of registration for foreigners, to give police officers power of arrest in cases brought under the Orders and to oblige ships' masters to enforce those Orders.

Penalties for contravention and for refusing to pay required recognizances were set at six months' imprisonment with or without hard labour.

The Act and the Orders also placed the burden of proof for proving their status on foreigners themselves.

One of the most notable innovations arising from the Act was the Metropolitan Police's Aliens Registration Office, opened in 1915.