The library system, which serves 1.3 million patrons, and records more than 1 million visitors each month, has about four dozen security cameras in 10 of its 46 libraries, says the report. The cameras were installed beginning in 2006, both inside and outside the buildings, because of requests by librarians faced with petty crimes, vandalism and graffiti.

According to the report, the issue over police access to video from the cameras came up in March, when a 77-year-old man was assaulted in the Woodmont Library parking lot, on Pacific Highway South in Des Moines. A man approached the library patron and asked for money. When the patron pulled out his wallet, the man stole it and pushed the library patron down, causing minor injuries.

As part of a Des Moines Police investigation, officers asked to see the tape from the security camera, but library officials said they wouldn't release it without a court order, the report said.

Police obtained a court order a week later and a suspect, a known transient, was arrested within 15 minutes of an officer viewing the tape, said Bob Collins, a Des Moines Police spokesman.

The decision to remove the security cameras "hinders our ability to do police work," Collins said in the report.

There should be no expectation of privacy in the library parking lot, said Des Moines Police Chief John O'Leary.

The most valuable time to solve a crime is right after it happens, and the library's warrant requirement delays that, O'Leary said. But the policy to require a court order is better than removing the cameras, he added. "My concern is it strikes me as a knee-jerk reaction," O'Leary said. "If the decision was simply to leave the cameras in and continue under current policy, I'd be happy with that."

Cameras outside in a parking lot are a gray area, said Ptacek in the report, but he views the library policy as part of "an important philosophy."

Ptacek, of the King County Library System, said cameras often provide a false sense of security, and there are enough staff members to visually supervise the libraries. "We're not in the business of surveillance," he said in the report.

He said he worries that the cameras might show what books patrons are checking out or what books they put in the book drop.

"Our philosophy is anything that reveals the use of the library or things (a patron) is using, it does require somebody to determine if we should turn that over," Ptacek said.

Removing the cameras isn't costing any extra money because it's being done as part of the normal course of work for facilities employees, according to the library system.

The camera removal will even save money because it costs $30,000 a year to maintain the cameras, Ptacek said in the report, "and $30,000 buys a lot of books."