They didn't look or act like the police officers in the famous black-and-white film clips, wading into crowds with billy clubs flying. These cops arrived on bicycles in department-issue short pants and quietly endured the taunting of demonstrators.
Chicago police passed that simple test on May Day, when they confronted a relatively small and well-behaved crowd. But the many thousands of protesters expected to gather next week for a summit of NATO leaders could pose a far greater challenge for a force that has embraced new crowd-control techniques but never completely shed its reputation for brutality.
Today, the city's officers know that if they so much as raise their clubs, the footage will be all over YouTube, reminding the world of what was called a "police riot" during the 1968 Democratic National Convention. Any misconduct could revive other embarrassments, too, such as detectives torturing confessions out of suspects and an off-duty officer's brutal beating of a bartender that was broadcast around the world.
The NATO protests are also a big test for Police Superintendent Garry McCarthy, who was selected last year by Mayor Rahm Emanuel to lead the 12,000-member force.
McCarthy, a former ranking commander in the New York Police Department, said he's committed to extracting troublemakers rather than overwhelming entire crowds, and he wants to change the way police view demonstrators.
"If you treat people as individuals, they're individuals," McCarthy said in an interview. "If you treat them as a mob, they become a mob."
For the city, the stakes could not be higher. With an international media corps attending the summit, a poor showing could be devastating to Emanuel's hopes that the event will lift Chicago into the top tier of global cities such as New York and Paris.
With more than 50 heads of state in town, police know they will be the front line.
"They know about the issues of the `60s and (want) to show the country how they've been trained and (that) they can do a good job," said Chuck Wexler, executive director of the Police Executive Research Forum in Washington, D.C.
McCarthy, he said, "learned from what departments did right and what mistakes they made. He's very sophisticated about demonstrations and about what has happened."
At the same time, Emanuel picked McCarthy in part because of his reputation for being tough. There is little doubt that his officers will do what it takes to put down any trouble.
In the ranks, officers quietly say they're worried about being understaffed, undertrained and blamed for anything that goes wrong. Many of them don't feel that their predecessors did anything wrong in 1968 after being provoked. And they won't hesitate to act if a comrade or bystander is attacked or rocks start shattering windows.
"I've seen the (protesters) on Facebook. They're saying `Come to Chicago and let's have a riot,'" said Lt. Robert Weisskopf, former president of the lieutenant's union. "We're not getting the library association coming to town. We're getting people coming that make soccer hooligans look like nice people."
In anticipation of the NATO summit, the department sent officers to Alabama to train at a Department of Homeland Security facility.
McCarthy has raised doubts about whether tear gas is an effective way to control a crowd, but his officers will have pepper spray. They will also have long-range acoustic devices known as sound cannons that can be used to neutralize crowds with ear-splitting noise. McCarthy said his intent is to use them only to get protesters' attention so police can better communicate with them.
"Our plan is not to disperse crowds," he said.
McCarthy found himself on the defensive earlier this year when it was reported that as chief of police in Newark, N.J, he allowed the NYPD's secretive Demographics Unit to spy on law-abiding Muslims in his city. McCarthy insisted his officers did not take part in the operations and then assured Chicago's Muslim community that police would not engage in any comparable type of surveillance _ a move that impressed the Muslim community.
The Chicago department has been trying to upgrade its tactics and procedures for years. A department that failed to adequately train, equip or even feed officers during the 1968 convention takes pains to make sure mistakes of the past are not repeated.
When Democrats brought their convention back to the city in 1996, those who were around in 1968 remembered the frayed nerves of officers who often had to wait and sweat for hours in cramped stations before they were ordered into the streets.
"We made certain they assembled in parks where they could throw a ball around and relax," said Matt Rodriguez, police superintendent in 1996.
Some officers turned the department's past into a joke with T-shirts that read "We kicked your father's ass, now it's your turn." But police took small steps to avoid confrontations, such as slathering a famous horse statue with grease to prevent anyone from climbing it. Back in 1968, someone attached a North Vietnamese flag to the figure.
Learning how to take abuse was a big part of the training in 2002, when the force prepared for a summit of trans-Atlantic business leaders.
"We dressed recruits like lunatics and gave them boxes of water balloons, silly string, Nerf bats and then took the coppers out there and made them take all that," said Jim Maurer, a young patrolman in 1968 who retired in 2005 as chief of patrol.
When the summit was over, Maurer said, police had made a total of three arrests.
The force also has made costly mistakes. In 2003, officers arrested 700 people during an Iraq war demonstration, some of whom were just passers-by. Just a few months ago, after a federal judge blasted the department for what he called unjustified arrests, the city agreed to settle a lawsuit for $6.2 million.
McCarthy, a former football player who's pored over videos of demonstrations as if they were game films, said he has not figured out "exactly what happened there." But when the Occupy protests came to Chicago last year, the department avoided the problems that marred demonstrations elsewhere. Arrests were made calmly and methodically, and everyone was given repeat warnings before being taken into custody.
Protest leaders said police were only behaving better only because they couldn't afford a public-relations nightmare ahead of the international summit.
"What they're doing is trying to step all over First Amendment freedoms without coming off as thugs," said Andy Thayer, one of the chief NATO protest organizers. "They're not stupid."
Associated Press Writer Tammy Webber contributed to this report.