Estonian citizenship - based primarily on the principle of jus sanguinis - is governed by 19 January 1995 law promulgated by the Riigikogu which took effect on 1 April 1995. The Police and Border Guard Board (Estonian: Politsei- ja Piirivalveamet) is responsible for processing applications and enquiries concerning Estonian citizenship.
Resolution Concerning the Citizenship of the Democratic Republic of Estonia, the first Estonian citizenship law was adopted by the Estonian National Council on 26 November 1918. According to this law, all people who
regardless of their ethnicity and faith were proclaimed Estonian citizens.
The Citizenship Law adopted in 1922 defined the principles of succession by applying the jus sanguinis principle.
Children born to parents, at least one of whom was an Estonian citizen at the time of birth (regardless of the place of birth) are automatically considered Estonian citizens by descent.
Children born in Estonia are eligible for Estonian citizenship if at least one parent holds Estonian citizenship at the time of birth.
A person who married an Estonian citizen before 26 February 1992 is eligible for Estonian citizenship.
Those seeking to become Estonian citizens via naturalisation are required to fulfill the following criteria:
Those who have committed serious crimes or are foreign military personnel on active duty are ineligible to seek naturalisation as an Estonian citizen.
'Undefined citizenship' (Estonian: kodakondsuseta isik, Russian: негражданин) is a term used in Estonia to denote a post-Soviet form of statelessness. It is applied to those migrants from former Soviet republics and their children, who were unable or unwilling to pursue any country's citizenship after the collapse of the Soviet Union. Russia being a successor state to the Soviet Union, all former USSR citizens qualified for citizenship of Russian Federation, available upon mere request, as provided by the law "On the RSFSR Citizenship" in force up to end of 2000. Estonia's policy of requiring naturalisation of post-war immigrants was in part influenced by Russia's citizenship law and the desire to prevent dual citizenship, and upon the established legal principle that persons who settle under the rule of an occupying power gain no automatic right to nationality. According to Peter Van Elsuwege, a scholar in European law at Ghent University, a number of historic precedents support this, most notably the case of Alsace-Lorraine when France on recovering the territory in 1918 did not automatically grant French citizenship to German settlers despite Germany having annexed the territory 47 years earlier in 1871.