WASHINGTON –

Shawn Nee, 35, works in television but hopes to publish a book of photographs. Shane Quentin, 31, repairs bicycles but enjoys photographing industrial scenes at night. The Los Angeles County Sheriff's Department probably wishes both would find other hobbies. Herewith a story of today's inevitable friction between people exercising, and others protecting, freedom.

When the Los Angeles Police Department developed a Suspicious Activity Report program, the federal government encouraged local law enforcement agencies to adopt its guidelines for gathering information "that could indicate activity or intentions related to" terrorism. From the fact that terrorists might take pictures of potential infrastructure targets ("pre-operational surveillance"), it is a short slide down a slippery slope to the judgment that photography is a potential indicator of terrorism, and hence photographers are suspect when taking pictures "with no apparent aesthetic value" (words from the suspicious activity guidelines).

One reason law enforcement is such a demanding, and admirable, profession is that it requires constant exercises of good judgment in the application of general rules to ambiguous situations. Such judgment is not evenly distributed among America's 800,000 law enforcement officials and was lacking among the sheriff's deputies who saw Nee photographing controversial new subway turnstiles. (Subway officials, sadder but wiser about our fallen world, installed turnstiles after operating largely on an honor system regarding ticket purchases.) Deputies detained and searched Nee, asking if he was planning to sell the photos to al-Qaida. Nee was wearing, in plain view, a device police sometimes use to make video and audio records of interactions with people, and when he told a deputy he was going to exercise his right to remain silent, the deputy said: