Not even ProPublica knows the source who provided blockbuster ‘Secret IRS Files’

Traditionally, media organizations prefer to know who is sending source material to have a better grasp of the authenticity of the material, the way in which it was obtained and the motivations of the sender. But, in this case, some journalists praised ProPublica for focusing on the veracity of the documents as the primary factor in deciding to publish, not the identity of the source.