South Australia's Attorney-General Michael Atkinson admits he misjudged public opinion on the state's attempt to curb political comment on the internet.

Mr Atkinson says he will repeal a law which would have meant that anyone posting comment or blogs during an election period would have had to give their real name and postcode.

Opponents had branded the law an attack on freedom of speech, and Mr Atkinson says he listened to community concerns in his decision to overturn it.

"I now understand that bloggers demand the right to publish, on the net, political commentary in the election period anonymously or under an assumed name," he said.

"I miscalculated the strength of feeling among teenagers and people in their 20s who have grown up with the internet and blogging and I underestimated their desire to have as a right the ability to make political commentary in the election period anonymously or under an assumed name.

"When one gets public opinion wrong, as I did, one has to change one's mind."

Free speech win

Civil libertarians say the Attorney-General's back flip is a win for free speech.

George Mancini of the SA Council for Civil Liberties says public outcry made the Government think twice.

"Nice little victory for democracy and freedom of speech in South Australia so that people don't need to be feared (sic) about speaking out and they can maintain their privacy," he said.

The state Opposition says Mr Atkinson should resign or be sacked.

The legislation was supported by the Opposition Liberal Party but shadow attorney-general Vickie Chapman now says the party was misled.

"He clearly wanted to use this legislation to hunt down any of those who criticised him or the Government and that was made absolutely clear yesterday by his statements and behaviour," she said.

"And indeed even the information and assurances were given by the Electoral Commissioner, [and] we consider she has been misled."

Ms Chapman says Mr Atkinson has become a liability to the Government.

Mr Atkinson promised to repeal the legislation retrospectively after the SA election on March 20.

But he later promised to act sooner to exempt internet sites from the new law.

"I will say Vickie Chapman has had an excellent idea on using the regulatory powers to exempt and that's just what we'll be doing as soon as possible, so congratulations to the Liberal Opposition spokeswoman for seeing a way through this problem," he said.