The Special Restriction (Coloured Alien Seamen's) Order is described by Laura Tabili as 'the first instance of state-sanctioned race discrimination inside Britain to come to widespread notice' (p. 56). The work of the Home Office Aliens Department, the Order was issued under Article II of the Aliens Order of 1920 and stated that 'coloured' seamen who did not possess documentary proof of their status as British must register as 'aliens' in Britain 'whether or not they have been in the United Kingdom for more than two months'. Police were to apprehend 'coloured' men disembarking from ships and report them to the police if they failed to show their documentation. In practice, it was not easy for 'coloured' seamen to prove that they were British subjects because sailors were not required to carry passports and, unlike those of their white counterparts, 'coloured' seamen's discharge certificates were not considered proof of their nationality because of allegations of trafficking in these papers.

Reasons for the issue of the Order are various and debated. In a letter dated 14 August 1926, the Under-Secretary of State cites the demands made at the end of the First World War by the National Sailor and Fireman's Union that 'steps should be taken to restrict the admission to this country of coloured seamen who could not establish that they were British subjects, since they competed in the overstocked labour market for seamen and were a source of grave discontent among British sailors', and claims that the accumulation of 'coloured seamen' in certain ports 'was a continual source of irritation and...likely to lead to a breach of the peace' (HO 45/12314). However, by the mid-1920s, employment in the shipping industry was beginning to pick up, which calls these reasons into question. Further, historians have recently questioned the role of the Union in pushing forward this piece of legislation, arguing that it was the state that played a more significant role.

State officials, determined to deport 'coloured' seamen, interpreted and enforced the rules rigidly, depriving these men of their citizenship. The India Office and Colonial Office received numerous protests from seamen who claimed that police were using the order to target men who were obviously British subjects. Further, officials erroneously applied the rules to non-seamen, for example registering 63 Glasgow-based Indians, most of whom worked as peddlers and labourers, as 'aliens'. Indians in Liverpool protested in the form of a public rally and through founding the Indian Seamen's Union, led by N. J. Upadhyaya. The India Office, fearful of the public outcry triggered by the Order in India, reprimanded the Home Office, even suggesting that all Indians should be issued with passports - a suggestion that was not received favourably by the Home Office. Finally, it was agreed that Indian seamen registered as 'aliens' could apply to the Home Office to have their British nationality verified. They would then be issued with a Special Certificate of Identity and Nationality which would enable their registration to be cancelled. The Order was finally revoked in 1942.

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.