Thanks to Andrew Carnegie, Pittsburgh has a long and proud history of public library service. But in the very region where the great push for modern public libraries in America began, one local politician has found something bad to say about community assets that need support.

Like many spurious political causes, Allegheny County Councilman Vince Gastgeb, a Republican from Bethel Park, is supposedly motivated by concern for children. He wants to deny county funding for eiNetwork, the Allegheny County Library Association's computer system that links 44 public libraries, if its filter systems can't keep out pornographic material.

With such an alarm sounded, someone might think libraries in the county are hotbeds of vice. In reality, they are centers of serious learning and improvement presided over by librarians, who rank among the most respectable members of society. It would be hard to find any group of people more dedicated and less inclined to tolerate those who would pollute their sanctum.

Even so, a man in the Bethel Park Library was found in February to be viewing nude images while seated next to two 12-year-old girls. But that situation resolved itself: The man was arrested and charged with disorderly conduct. If anything, it is proof that the library system works.

As most computer-savvy Americans know, the most sophisticated filter systems have their flaws. Moreover, some filters can be so fine that legitimate Web searches -- such as for breast cancer -- will fail. For dedicated librarians, this presents a problem not of their making. Yet nothing suggests that they aren't up to the task of balancing First Amendment concerns, compliance with the law and protection of children. Moreover, as ACLA Executive Director Marilyn Jenkins points out, the system is in full compliance with federal and state regulations.

With gross irresponsibility, the councilman threatens to lobby for the withholding of Regional Asset District funds from the library computer system if the porn filters don't block all indecency. If his council resolution succeeds, the undeserved punishment of the libraries would have the perverse effect of making children and adults suffer -- and that would be a real obscenity.