Why did Gandhiji decided to launch a nationwide Satyagraha against the proposed Rowlatt Act 1919?

Gandhiji in 1919 decided to launch a nationwide satyagraha against the proposed Rowlatt Act (1919) due to the following point
• This Act had been hurriedly passed through the Imperial Legislative Council despite the united opposition of the Indian members.
• It gave the government enormous powers to repress political activities,
• According to this act detention of political prisoners without trial for two years. Mahatma Gandhi wanted non-violent civil disobedience against such unjust laws, which would start with a hartal on 6 April.