In 2013, Amadou joined the opposition to President Issoufou, although he remained in his post as President of the National Assembly. On 27 August 2014, the National Assembly's leadership, in response to a request from the government, decided to allow the arrest of Amadou, who was not present, in connection with an investigation into an illegal network trafficking infants from Nigeria. One of his wives had already been arrested. Within hours of the decision, Amadou fled to Burkina Faso. He had denounced the investigation, and his supporters argued that constitutionally he could only be arrested if his parliamentary immunity was removed through a vote of the National Assembly as a whole.