The following is a guest post by Justine Forcina, a foreign law intern working with Foreign Law Specialist Jenny Gesley at the Global Legal Research Directorate of the Law Library of Congress. This post is part of our Frequently Asked Legal Questions series.
Each year on October 3, Germany celebrates the anniversary of its reunification. This year, 2025, marks the 35th anniversary.
After World War II, Germany was divided among the four victorious powers: the United States, the United Kingdom, and France controlled West Germany, while the former Soviet Union controlled East Germany. Even Berlin, the capital, was divided into East and West Berlin, separated by the Berlin Wall. The fall of the Berlin Wall in 1989 paved the way for the reunification of Germany after 45 years of division. Through a series of legal agreements and political negotiations, the German Democratic Republic (GDR) joined the Federal Republic of Germany (FRG), formally ending the separation of East and West Germany.
What Role Did the Berlin Wall Play in Germany’s Reunification?
The Berlin Wall, built in 1961, stood as the most visible symbol of Germany’s division for almost 30 years. It separated the city, restricted movement, and many who tried to escape across the border at the Berlin Wall were shot and killed. In the late 1980s, growing protests and increasing emigration to West Germany weakened the East German regime. On November 9, 1989, an official in East Germany’s ruling Socialist Unity Party (Sozialistische Einheitspartei Deutschlands, SED), Günter Schabowski, mistakenly announced that new travel rules for East Germans would apply “effective immediately.” This announcement led thousands to storm the border crossings, resulting in the opening of the Berlin Wall. Its fall became a decisive moment on the way to German reunification and a symbol of the end of the separation of Germany.
How Did Negotiations Towards Reunification Begin?
After the fall of the Berlin Wall, the situation developed rapidly. The collapse of communist regimes across Eastern Europe, combined with the economic weakness of the GDR, led to a reassessment of political and economic policies in the region. In March 1990, the first free elections in the GDR took place, resulting in a victory for the “Alliance for Germany,” a coalition that strongly supported reunification. Negotiations between East and West Germany began immediately, while international discussions with the Allied powers addressed broader issues of sovereignty and security.
What Is the Unification Treaty?
The Unification Treaty (Einigungsvertrag) is the agreement between the FRG and the GDR that established German unity. It was signed on August 31, 1990, and entered into force on October 3, 1990. The treaty regulated the accession of the GDR to the FRG under the framework of the former article 23 of the German Basic Law. It also unified Berlin as a federal state and the capital of Germany. The Unification Treaty addressed a wide range of issues, including the reorganization of public administration, the assumption of the GDR’s assets and debts, and the adoption of West German laws. The treaty also established the five new federal states (Mecklenburg-Vorpommern, Brandenburg, Saxony, Saxony-Anhalt, and Thuringia) as members of the Federal Republic.
What Did the Previous Version of Article 23 of the Basic Law Regulate?
The previous version of article 23 allowed other German territories to accede to the Federal Republic by declaration. This was the legal mechanism used for the GDR to join the FRG. After reunification, article 23 was amended, and today it regulates Germany’s role in the European Union. Reunification was not legally a merger of two states into a new entity, but rather the accession of the GDR to the existing Federal Republic, as per article 23. The FRG continued as the same legal subject under international law, while the GDR ceased to exist.
What Was the Two-Plus-Four Treaty?
A requirement for the entry into force of the Unification Treaty under international law was the prior consent of the four victorious powers of World War II: the United States, the United Kingdom, France, and the former Soviet Union. This was achieved through the Two-Plus-Four Treaty (2+4-Vertrag), which was signed in Moscow on September 12, 1990, and entered into force on March 15, 1991. The “two” refers to the two German states (FRG and GDR), and the “four” refers to the four allied powers. The treaty confirmed Germany’s full sovereignty, final borders, and the withdrawal of Allied rights, formally ending their authority over Germany. It also regulated security matters, including Germany’s commitment to remain in NATO while limiting the stationing of foreign troops. With these international agreements, German unity was secured. The possibility of reunification had already been anticipated in West Germany’s Basic Law of 1949, as explained above.
Why Was the Basic Law of West Germany Not Called Constitution?
When the Basic Law (Grundgesetz, GG) entered into force on May 23, 1949, it was deliberately named “Basic Law” instead of “Constitution” because it was intended as a provisional framework for West Germany until national unity could be restored. Article 146 of the Basic Law still states that “[t]his Basic Law shall cease to apply on the day on which a constitution freely adopted by the German people takes effect.” Although article 146 provided for a new constitution, in practice, the Basic Law was simply extended to the new federal states on October 3, 1990, thus becoming the constitution of a united Germany, a moment still celebrated each year.
Happy anniversary, reunited Germany!
Subscribe to In Custodia Legis – it’s free! – to receive interesting posts drawn from the Law Library of Congress’s vast collections and our staff’s expertise in U.S., foreign, and international law.
blogs.loc.gov · Public Domain