Gandhiji decided to launch nationwide satyagraha against Rowlatt Act in 1919 because of the following reasons :
(i) The terms and conditions of Rowlatt act were very obnoxious, they are violating the civil rights of Indians.
(ii) This act had been hurriedly passed through the imperial legislative council despite the united opposition of the Indian members.
(iii) Moreover, Gandhiji had already seen the success in satyagraha movements in regions like Champaran, Kheda. These had prepared the ground for a nation-wide satyagraha.