A group of alleged so-called Reichsbürger centred around Prince Heinrich XIII of Reuss goes on trial in the German city of Frankfurt on Tuesday. They are accused of plotting to overthrow the state.
Germany's Reichsbürger scene is considered violent and steeped in conspiracy theories and far-right ideology.
Reichsbürger, or "Citizens of the Reich," claim the historical German Reich, founded in 1871 with an emperor at the head, continues to exist and did not end with Germany's defeat in the Second World War in 1945.
They do not recognize the Federal Republic of Germany, or its constitutional structures such as parliament. They also do not believe they should pay taxes, fines or social security contributions. Germany's domestic intelligence service estimates there are around 23,000 people in the scene.
However, the Reichsbürger movement is not a monolith. Some see themselves as heads of state of their own little empires with their own ID cards and licence plates. The Federal Office for the Protection of the Constitution calls these people "self-administrators".
Anti-Semitism plays an important role in their extreme right-wing ideology. This includes the denial of the Holocaust and the promotion of the "Deep State" myth, according to which secret powers control world events.
The false belief that Germany is still occupied by the four victorious powers of the Second World War - the US, the former USSR, France and Britain - is also widely held within the movement.