Mitbestimmungsgesetz (in English, Codetermination Act) of 1976 is a German law which requires companies of over 2000 employees to have half the supervisory board of directors as representatives of workers.
The Act was passed on May 4 after long consultations and debates in Parliament (the Bundestag). This law was a political compromise between the Social Democrats and Liberal coalition members; it reconciled views of individual employee participation in decision-making with the less conservative view of collective codetermination of labor. The 1976 law applies to all corporations with more than 2,000 employees; a similar law was passed in 1951 but only applied to coal and steel companies. (It remains in force and applies from 1,000 employees on in these branches' companies.) 
This co-determination law is the most recent in a line of laws in Germany, originating with the 1920 “Works Council Act.” However, the impetus for a movement towards co-determination in Germany stems from the Weimar Constitution after World War I, which, in 1919 said that, “Works and staff are appointed to participate with equal rights together with the company in the regulation of wages and working conditions, as well as in the complete economic development of the producing powers.”
It applies to all German capital companies, including public companies (Aktiengesellschaft), cooperatives (eingetragene Genossenschaft), private limited companies (Gesellschaft mit beschränkter Haftung) and partnerships (Kommanditgesellschaft auf Aktien) if they have over 2000 employees. Employees and national unions have equal representation on the supervisory board with the stockholders, but the board’s chairman must be a stockholder who has a tie-breaking vote.
The principle is to have almost equal representation between employee representatives and shareholder representatives on the supervisory board (Aufsichtsrat). Germany company law has two levels of boards of directors. The supervisory board then elects a management board which leads the company. The head of the supervisory board is always a shareholder representative who has two votes in case of a deadlock. (Coal and steel industry companies' co-determination goes even further with full parity and a neutral tie-breaking member, instead) 
Under the Codetermination Act, the supervisory board must have 12, 16 or 20 members depending on the company's size. Two or three seats will usually be reserved for union representatives. the other seats will be workers, officials and appointees of other interest groups.
Companies with equal representation on their boards must have a dedicated management board position for labor affairs. Codetermination allows employees and not only unions to influence the operations of firms and their surplus.
While this law was in some ways an extension of the codetermination law of 1951, it differed in key ways. Unlike the 1951 law, however, employees choose their representatives rather than being chosen by the national union; this had the effect of weakening union power. However, employees can use codetermination to protect themselves against wage cuts, layoffs and restructuring, and for this reason, it is believed that wage structure in Germany is remarkably stable.
Former Chancellor Gerhard Schröder established a Commission on Codetermination (Mitbestimmungskommission), which in 2005 came to no conclusion about possible reforms of the law. Different members disagreed with one side wanting to reduce worker influence and the other side increase it.
- Thimm, Alfred L. (1981). "How Far Should German Codetermination Go?". Challenge. 24 (3): 13–22. doi:10.1080/05775132.1981.11470696. JSTOR 40719972.
- "MontanMitbestG - Gesetz über die Mitbestimmung der Arbeitnehmer in den Aufsichtsräten und Vorständen der Unternehmen des Bergbaus und der Eisen und Stahl erzeugenden Industrie". www.gesetze-im-internet.de (in German). Retrieved 2018-12-03.
- Page, Rebecca (2001). Co-determination in Germany: A Beginners' Guide (PDF). Hans-Böckler-Stiftung.
- WALTHER MULLER-JENTSCH “Reassessing Codetermination” p39-56 The Changing Contours of German Industrial Relations. 2003. Paperback.
- Gorton, Gary (2004). "Capital, Labor, and the Firm: A Study of German Codetermination". Journal of the European Economic Association. 2 (5): 863–905. doi:10.1162/1542476042782260. JSTOR 40005074.
- E McGaughey, 'The Codetermination Bargains: The History of German Corporate and Labour Law' (2016) 23(1) Columbia Journal of European Law 135
- Mitbestimmungsgesetz Urteil BVerGE 50, 290