At Montgomery County public libraries, it's no more Mr. Nice Guy.

In July, a new software system began enforcing a five-year-old rule that patrons spend no more than one hour per 24-hour period using a public computer at any county library. And county agencies are finalizing guidelines that will allow library branch managers to ban people they deem "disruptive" from a library for up to 90 days.

The software system is provoking some complaints. Vanessa Michener, 24, a math and social studies teacher who recently moved to Montgomery from Frederick, said she was dismayed Oct. 11 when the software logged her off a computer she was using in the Olney branch.

The time limit, she said, makes it impossible to conduct any serious research. "There's no way that 60 minutes in 24 hours, for any student or professor, is a sufficient amount of time," she said.

The American Civil Liberties Union objected early this year to Montgomery's countywide "disruptive behavior" law, saying that it allows a single official -- such as a library manager or a Ride On supervisor -- to accuse a person of disruptive behavior and then decide whether a ban is warranted, effectively combining the functions of an arresting officer and a judge. But council members, in approving the measure June 15, said it would withstand constitutional challenge.

Under the law, people using a county facility must not act in a way that "a reasonable person would find disrupts the normal functions being carried on at that public facility." A person who engages in such activity must "accurately identify himself or herself" when asked by the facility manager.

If the person continues acting in a disruptive manner, the manager can write an order banning the person for up to 90 days; in the case of transit vehicles, the order can ban the person from the entire county transit system for that period. The order can also "impose any other reasonable condition" to ensure that a facility's normal functions are not disrupted.

A banned person would have an automatic hearing the next business day by the county's chief administrative officer or an assistant chief administrative officer.

Harriet Henderson, director of the county's department of public libraries, said county officials would begin applying the law by the end of this month, once forms have been printed and procedures are in place.

She said the law gives county officials new flexibility. Until now, librarians and other officials have had to call police to deal with unruly patrons, which sometimes resulted in one-year "no trespass" orders. "I don't think this is saying we're toughening up," she said of the new software and the law. "It's saying were going to address [these issues] in a more appropriate way."

She said a person who continues loudly using a cell phone in a library -- after being directed to an appropriate area for cell phone conversations -- might receive a one-day ban. Someone behaving "very aggressively" might get 90 days.

Henderson said she has heard complaints from library computer patrons who were logged off even though empty terminals were available. At the Rockville branch last week, several terminals were unused, but their screens indicated that only 60 minutes of use was permitted.

Although libraries may occasionally have unused terminals, Henderson said, the new software is indicating that computers are being used to capacity at certain times of the day.

She said the new software would be reviewed after its first six months. "It's fairly common for libraries to have a one-hour limit for public Internet access," she said. County libraries have had the limit since 1999, but the new software enforces it more rigorously than in the past, when library staffers manually kept track of computer use.

Montgomery's library system maintains 450 computers for public use at 21 of its 22 branches. In July and August, said public services administrator Rita Gale, the libraries were visited nearly 1.1 million times.

After Michener was automatically logged off the computer she was using in Olney, she learned that driving to another library wouldn't gain her any more time: The system monitors use countywide. She began calling county officials to complain, eventually reaching the office of County Executive Douglas M. Duncan (D).

Informed that Duncan was not in at the time of her call, she asked whether she might use his computer. The request was denied.