The plaintiff in the case sought the issuance of an Estonian citizen's ID and passport from the Police and Border Guard Board (PPA) on the grounds that his grandfather had opted for Estonian citizenship under Article IV of the Tartu Peace Treaty. The plaintiff argued that as this was the case, his mother, and thus he as well, was a citizen of Estonia by birth.

The PPA and two lower tiers of court in Estonia disagreed on the grounds that the plaintiff's grandfather did not fulfill the requirement set out in the peace treaty that such people must leave the territory of Russia.

Establishing an Estonian citizenry abroad could not have been a goal of the Tartu Peace Treaty of 1920, the court stated in its decision, as it would have differed from the international practice of the time and made impossible the checks against the prohibition on dual citizenship imposed with the regulation "On the Citizenship of the Democratic Republic of Estonia" and subsequent Estonian citizenship laws.

Article IV of the peace treaty gave Estonians who opted for Estonian citizenship, commonly known as optants, one year to resettle to Estonia. When this was prevented by objective circumstances, the Estonian state sometimes also accepted later arrivals. Hence the desire of a person to identify themselves unambiguously as a citizen of Estonia who lives in Estonia was crucial, according to the Supreme Court.

This is something that the plaintiff's grandfather, like many others who opted for Estonian citizenship but continued to live outside the territory of Estonia as citizens of the Soviet Union, never did, the top court added.

The granting of a certificate of the acceptance of citizenship to an optant did not automatically mean the acquisition of citizenship; citizenship was obtained by an optant upon their arrival in Estonia.

The acquisition of citizenship could not have been completed via arrival in occupied Estonia, or Estonia after 1940, as it was not possible for de facto Estonian authorities to accept such arrivals.

It was also not possible for the plaintiff to obtain Estonian citizenship via his mother, as all persons with respect to whom the certificate of the acceptance of citizenship was valid were listed in the certificate by name. The plaintiff's mother, who was born in 1925 and arrived in Estonia in the 1940s, was not listed on the certificate of acceptance of citizenship. 

Friday's decision of the Supreme Court does not apply to individuals whom the PPA has already previously deemed as citizens of Estonia on the same basis. Such law-abiding citizens are not faced with the prospect of being stripped of their Estonian citizenship.