What’s a blogger’s worst nightmare? It might be getting a subpoena, demanding information that would help identify anonymous posters to a site.

It happened to Ben Smith, co-founder of Room 8, a site where people post items about New York politics. Earlier this year, Smith got a subpoena from the Bronx DA’s office, which demanded the IP addresses of the blogger “Republican Dissident” as well as several other anonymous posters who used news reports about investigations as a jumping off point to criticize Republican officials. When Smith asked why the DA wanted the information, prosecutors refused to say. To make matters worse, the DA’s office required that the subpoena be kept secret, claiming that disclosure of its existence could impede an investigation.

Smith called Public Citizen, which agreed to represent him pro bono. (See today’s New York Times story for more details. As Jonathan Glater eloquently writes, “This, of course, is a blogger’s nightmare: enforced silence and the prospect of jail time.” ) Public Citizen filed a motion to quash the subpoena and argued against the proceedings being secret.

The DA finally came to its senses and backed down; now the DA’s office claims that its head honcho never knew about the attempt to ferret out his critics.

Said Paul Alan Levy, the Public Citizen attorney who represented Smith: “This is the latest of several reports (here and here) about law enforcement officials demanding identifying information about political bloggers. A useful solution to the problem might be the creation of mandatory guidelines that forbid the issuance of law enforcement subpoenas for bloggers without the express involvement of the district attorney himself so that he can be held accountable when it turns out that the subpoena was issued irresponsibly.”