"The fact of the matter is, we live in the United States, not the old Soviet Union," he said.

A rep for the American Civil Liberties Union of Illinois said he did not know of any state or federal laws barring photography at train stations or similar public facilities. Such a ban could be challenged under the freedom of expression clause of the First Amendment, ACLU spokesman Ed Yohnka said.

This isn't the first time rail station shutterbugs have come into conflict with transit agencies balancing safety and security with a popular pastime.

Last year, two Homewood men were detained by police for taking pictures from a Metra platform in Morton Grove.

Metra allows photography on its property as long as people are not trespassing or endangering themselves, Metra Police Chief James Sanford said.

The police department also reserves the right to question people "taking photos that we don't feel would be of interest to rail fans and tourists," Sanford said.

Union Pacific has its own police officers to enforce the ban, which is similar to one proposed in 2004 by the New York City Transit branch of the Metropolitan Transit Agency. When riders complained and lawsuits were threatened, the MTA proposal was dropped.