Given the substantial number of Europeans who left Europe for other continents in the 1800s and 1900s, and the extension of citizenship by descent, or jus sanguinis, by some European countries to an unlimited number of generations of those emigrants' descendants, there are potentially many tens of millions or even hundreds of millions of persons currently outside Europe who have a claim to citizenship in an EU member state and, by extension, to EU citizenship.[11] If these individuals were to overcome the bureaucratic hurdles of certifying their citizenship, they would have freedom of movement to live anywhere in the EU, under the 1992 European Court of Justice decision Micheletti v Cantabria.[11][12]