The founder of the pro-democracy group Hiến Pháp, he played an organising role in the 2018 Vietnam protests; he was arrested shortly afterwards on charges of posting anti-government material on social media, and served a five year custodial prison sentence before being released in 2024.
Ca lives in Hồng Ngự district, Đồng Tháp province, with his wife, Phạm Thanh Tâm, with whom he has at least three children.
[5][2] A government-run newspaper subsequently reported that Ca had used Facebook and YouTube to publish information that "fabricated and distorted" Communist Party policies and guidelines, as well as to slander local government leaders and the police.
[5] During his detention, Ca's wife Tâm received donations from the 50k Fund, which provided financial support to the families of imprisoned activists.
[2] During his imprisonment, Ca took part in two hunger strikes, citing poor conditions and food, as well as a lack of water and medical treatment.
[10] Ca's family raised concerns around his health needs being neglected, stating that he had diagnoses of lung disease and diabetes, as well as stomach problems; they also shared he had been placed into cells with inmates who had physically assaulted him.
[10] On 19 March 2019, Amnesty International issued a public statement calling on the Prime Minister of Vietnam, Nguyễn Xuân Phúc, to release Ca.