The 1905 Aliens Act declared that 'undesirable immigrants' would be denied entry to Britain. Although it was vaguely worded, the restrictions were mostly levied against Jewish and Eastern European immigrants.

The 1905 Aliens Act did not discriminate against immigrants from the Indian subcontinent, who as subjects of the British Empire were granted free movement at this time. However, earlier Navigation and Merchant Shipping Acts had discriminated against seafarers from the Indian subcontinent. It was after the First World War that amendments to immigration rules and restrictions on 'coloured seamen' came to discriminate against South Asian migrants more formally (e.g. the Special Restriction (Coloured Alien Seamen Order)).

The Aliens Order 1920 was an amendment to the Aliens Restriction Act of the previous year. Brought out in the context of widespread unemployment after the First World War, it required all aliens seeking employment or residence to register with the police. Failure to do so would result in deportation. Further, under the Order, the Home Secretary retained the power to deport any alien whose presence was considered detrimental to the public good. Constitutionally, South Asians were not ‘aliens’ but rather citizens of the British empire. In spite of this, however, many lascars were caught up in this legislation. They were not generally issued with passports so could not prove their status as British citizens and their exemption from the Order. Hence, many were subject to harassment and denied employment.

The 1919 Aliens Restriction Act extended the powers of the wartime Act of 1914 which obliged foreign nationals to register with the police, enabled their deportation, and restricted where they could live. The primary aim of the 1914 Act was to target ‘enemy aliens’ resident in Britain during the First World War. The 1919 Act continued these restrictions into peace-time and extended them. It restricted the employment rights of aliens resident in Britain, barring them from certain jobs (in the civil service, for example), and had a particular impact on foreign seamen working on British ships. It also targeted criminals, paupers and ‘undesirables’, and made it illegal for aliens to promote industrial action. A motivation for the extension of the restrictions was the end to the wartime labour shortages and consequent desire to safeguard jobs for indigenous white Britons.

South Asians were not formally classified as ‘aliens’ as they were citizens of empire. However, many were harassed because of the legislation. The 1919 Act was renewed annually until 1971 when it was replaced by the Immigration Act.