The government has published its Immigration Bill, which will change the rules on access to the NHS and impose tougher penalties for illegal working. But what legislation has been passed over the last century or so?
Aliens Act 1905
This targeted "undesirable aliens" - such as paupers, lunatics, vagrants and prostitutes - who could be refused entry.
This granted the common status of British subject upon those persons who had specified connections with the Crown's dominions.
The Empire's dominions each adopted their separate citizenships, but retained the common status of British subject.
This required certain potential migrants to supply proof that either they, their parents or grandparents had been born in Britain.
Commonwealth citizens lost their automatic right to remain in the UK, meaning they faced the same restrictions as those from elsewhere. They would in future only be allowed to remain in UK after they had lived and worked here for five years.
A partial "right of abode" was introduced, lifting all restrictions on immigrants with a direct personal or ancestral connection with Britain.
This act ensured that only one wife or widow of a polygamous marriage had a right to enter the country.
It also ensured people with freedom of movement in the European Community did not need leave to enter or remain in the UK.
It became a criminal offence to employ anyone unless they had permission to live and work in the UK.
The act removed benefits from asylum seekers and created the National Asylum Service to house them, taking pressure off local authorities.
This created the first English test and citizenship exam for immigrants and introduced measures against bogus marriages.
This act introduced a single form of appeal that remains to this day and made it a criminal offence to destroy travel documents. It limited access to support for those told to leave the UK.
A five-tier points system for awarding entry visas was created.
Those refused work or study visas had their rights of appeal limited.
The act brought in on-the-spot fines of £2,000, payable by employers for each illegal employee, which could include parents taking on nannies without visas.
This provided the UK Border Agency with powers to tackle illegal working and automatically deport some foreign nationals imprisoned for specific offences, or for more than one year.
It gave immigration officers police-like powers, such as increased detention and a search-and-entry roles.
The act brought in the power to create compulsory biometric cards for non-EU immigrants.
This act amended the rules so people from outside the European Economic Area had to have residential status for eight years before being eligible for naturalisation.
Those seeking naturalisation through wedlock had to be married for five years first.
The act also allowed immigration and customs officers to perform some of each other's roles and imposed a duty on home secretaries to safeguard children.