A few cases of full currency substitution prior to 1999 had been the consequence of political and historical factors. In all long-standing currency substitution cases, historical and political reasons have been more influential than an evaluation of the economic effects of currency substitution. Panama adopted the US dollar as legal tender after independence as the result of a constitutional ruling. Ecuador and El Salvador became fully dollarized economies in 2000 and 2001 respectively, for different reasons. Ecuador underwent currency substitution to deal with a widespread political and financial crisis resulting from massive loss of confidence in its political and monetary institutions. By contrast, El Salvador's official currency substitution was a result of internal debates and in a context of stable macroeconomic fundamentals and long-standing unofficial currency substitution. The eurozone adopted the euro (€) as its common currency and sole legal tender in 1999, which might be considered a variety of full-commitment regime similar to full currency substitution despite some evident differences from other currency substitutions. For more on dollarisation, cf. Fields, David, and Matías Vernengo. "Dollarization." The Wiley-Blackwell Encyclopedia of Globalization (2013).