[3] The first legal arrangements for Portuguese citizenship were created through the 1603 Ordination of King Philip II of Portugal (the Ordenações Filipinas).
Children born outside Portuguese territory did not receive citizenship unless their in-wedlock father or out-of-wedlock mother was in royal service abroad.
[4] The 1867/1868 Civil Code provisions provided the details for the 1826 charter's broad language, including the ability for a child to opt out by declaration from the automatic jus soli citizenship for persons born in Portugal to a foreign father or out-of-wedlock mother.
[4] Loss occurred with naturalisation in another country (but only for the individual concerned, not a wife or child unless they declared otherwise); accepting without permission a foreign government's public office, pension, or honors; expulsion by judicial decision; and marriage by a Portuguese woman to a foreign man if the woman acquired her husband's citizenship by marriage.
Decree-Law 308/75 of 24 June 1975 was a response to the loss of Portuguese citizenship by many people born in former territories of Portugal in Africa and elsewhere that had acquired independence.
The legislation was the source of confusion and object of criticism, for, among other reasons, its inherent removal of citizenship from some persons and its path to statelessness for others.
[4][6] Special rules exist concerning the acquisition of Portuguese citizenship through connections with Angola, Brazil, Cape Verde, Goa, Guinea Bissau, Mozambique, Macau and São Tomé and Príncipe.
[7] Although most residents of these territories were given a choice between acquiring Indian citizenship and retaining their previous nationalities, those from Dadra and Nagar Haveli were not.
[8] In Goa, Daman and Diu, residents automatically became Indian citizens on 20 December 1961 unless they had made a written declaration before this date stating their intention to retain their existing nationality.
[9] Portugal did not recognise the annexation of its former Indian territories;[10] persons born in Goa before 19th December 1961 were recognized as Portuguese citizens.
The Australian immigration authorities argued that if East Timorese were Portuguese citizens, they should be expected to seek protection there and not in Australia.
It is no longer possible to acquire Portuguese citizenship by connection with Macau before 3 October 1981 and after 20 December 1999 transfer of sovereignty to China, except by birth or association with the territory previous to that date.
[18] The Portuguese Constitution of 1976 introduced the principles of non-discrimination on the basis of sex and marital status of parents at birth, and a fundamental right to citizenship.
The political parties of Portugal agreed that new nationality legislation was required to achieve compatibility with the constitution, and finally approved it in 1981.
[4] Jus soli citizenship, in contrast, was restricted to require expression of intent and either of the parents having lived in Portugal for at least six years beforehand.
[19] Portuguese citizens have since been able to work in other EC/EU countries under the freedom of movement for workers established by the 1957 Treaty of Rome[20] and participated in their first European Parliament elections in 1987.
[21] With the creation of European Union citizenship by the 1992 Maastricht Treaty, free movement rights were extended to all nationals of EU member states regardless of their employment status.
[22] The scope of these rights was further expanded with the establishment of the European Economic Area in 1994 to include any national of an EFTA member state except for Switzerland,[23] which concluded a separate free movement agreement with the EU that came into force in 2002.
[24] In response to an increase in the 1990s of unlawful immigration into Portugal, the governing coalition amended the 1981 act by limiting jus soli and naturalisation.
[4] The election of a Socialist Party-led government in 2005 gave rise to the passage of a bill to modernize Portuguese nationality law, in recognition of the impact of years of immigration into the country.
[4] The objectives were to integrate second- and third- generation immigrants who did not have citizenship, to comply with judicial and legal demands that the nationality law be consistent with the European Convention of Nationality and its non-discrimination clauses, and to lessen confusion of outdated wording and definitions that relied on simple regulation instead of law.
[4] Double jus soli was introduced, with citizenship automatically extended to individuals with a parent also born in Portuguese territory who resided there at the time of the child's birth.
[4][25] Naturalisation for children was made available to those who had a parent who resided legally in Portugal for at least five years or who completed the first cycle of basic education.
[40] Any person convicted of a crime resulting in imprisonment for more than three years or who otherwise presents a threat to national defence is barred from naturalising.
Women who lost Portuguese citizenship by marriage to foreign men are able to able to apply for reacquisition without being subject to the non-opposition requirement.
'[44] In 2020 there were reports that changes to the Law of Return were proposed which would restrict eligibility for citizenship to people who had lived in Portugal for two years.
[citation needed] The Portuguese parliament passed legislation facilitating the naturalisation of descendants of 16th-century Jews who fled because of religious persecution.
Furthermore, applicants must be able to prove an "emotional and traditional connection with the former Portuguese Sephardic Community," commonly established through a letter from an Orthodox rabbi confirming Jewish heritage.
[55] After some notorious cases where it was reported that people without a valid claim had been granted citizenship, with falsification of documents and other misdeeds, the Portuguese government on 9 March 2022 implemented a decree-law to increase scrutiny of candidates, who will have to prove an "effective connection with Portugal".
[56] Among cases being investigated was that of Russian billionaire Roman Abramovich, although it was not expected that changes would be retroactive for people already granted citizenship.