Journalism academics and the union have backed source protection for bloggers and other citizen journalists, rejecting Coalition concerns that Labor's shield laws legislation will weaken the policy objective they're designed to serve.

But Dr Johan Lidberg from Monash University's School of Journalism still sees problems in the new legislation, saying the laws don't go far enough in offering legal protection for journalists and their sources.

Shadow attorney general George Brandis criticised the new laws in an opinion piece published in The Australian yesterday. Striking out at the Greens for amending the bill to extend journalistic protection for bloggers and tweeters, Brandis suggests that instead of a win for journalists and their sources, the new laws are likely to weaken the very policy objective they purport to serve.