The Supreme Court on Wednesday questioned the government's broad use of an exemption in the federal Freedom of Information Act to withhold documents from the public.

WASHINGTON — The Supreme Court on Wednesday questioned the government's broad use of an exemption in the federal Freedom of Information Act to withhold documents from the public.

The justices heard arguments in an appeal from Glen Milner, a Washington state resident who sued under FOIA for maps showing the extent of damage expected from an explosion at the Navy's main West Coast ammunition dump on an island near Port Townsend in western Washington.

The Obama administration is defending the decision to deny Milner the maps under a provision of FOIA that exempts from disclosure documents "related solely to the internal personnel rules and practices of an agency."

Chief Justice John Roberts said the administration was asking the court "to torture the language in FOIA" to keep the documents from being made public. Roberts also noted the public's frustration with FOIA, even when the government is willing to turn over material. "It takes forever to get the documents," he said.

Several other justices indicated that they also thought the government and several appeals courts that have dealt with FOIA lawsuits have interpreted the exception too broadly.

"If the agency has a rule that says put explosive A in building 1 and put explosive B in building 2, that's hard for me to explain that it's just a personnel rule, other than, as Justice Scalia says, everything. All functions have to be undertaken by humans," Justice Anthony Kennedy said.

But Kennedy also said that a victory for Milner might mean that the government stamps more documents as classified, which makes them unavailable under FOIA.

The case before the court revolves around competing ideas of public safety. The government says that releasing the maps could allow someone to identify the precise location of the munitions that are stored on Indian Island.

Justices Samuel Alito and Stephen Breyer appeared most sympathetic to the government's view.

"The Navy thinks, rightly or wrongly, that they don't want these maps circulated because they think it would make it easier to blow up the munitions," Breyer said. "They want the firemen to have them, they want the civil defense workers to have them, but they don't want people who might blow them up to have them."

On the other hand, Milner argues that the people who live nearby have valid reasons for wanting to know whether they would be endangered by an explosion.

"Can the public seek information that places the community at a severe security risk? Is it possible for us to say that that kind of information ... could not be legitimate public information?" Justice Sonia Sotomayor asked.

An explosion at the Navy's Port Chicago ammunition depot during World War II killed 320 people.

Milner is a longtime community activist who is concerned about safety issues at several area naval facilities. His lawyer, David Mann, also pointed out what he described as the arbitrary nature of the government's responses to document requests.

While one Navy official refused to release the map from the ammunition dump, an official at a nearby submarine base provided Milner the map showing the probable range of damage from an explosion there.

The Associated Press is among 20 news media organizations that filed a brief urging the court to limit the government's invocation of the personnel exemption.

A decision is expected before summer.

The case is Milner v. Department of the Navy, 09-1163.