Why was there constitutional crisis during 1955 to 1956?

Answer: The Coloured vote constitutional crisis

Was the response of the South African apartheid regime to the adoption of the Freedom Charter at the People's Congress in Kliptown on June 26, 1955.

The 156 defendants were charged with high treason, a charge that led to the death sentence. The defendants were finally found to be "innocent," but some of them were later convicted at the Rivonia Trial.