A Cook County judge on Friday declared the state's controversial eavesdropping law unconstitutional, securing an important victory for activists who want to videotape the police in public but muddying the legal waters as the city gears up for potentially thousands of demonstrators for the G-8 and NATO summits in May.

In a 12-page decision, Criminal Courts Judge Stanley Sacks ruled that the law is too broad and potentially criminalizes "wholly innocent conduct." He cited as an example a parent recording her child's soccer game and inadvertently capturing a conversation between two bystanders.

"Although it is extremely unlikely that this doting parent would be charged with a felony offense, the fact remains that she could, thusly punishing innocent conduct," Sacks wrote.

The decision came in the case of Christopher Drew, an artist who was arrested in 2009 for selling art on a Loop street without a permit. Drew was charged with eavesdropping after he used an audio recorder in his pocket to capture his conversations with police during his arrest.

In a statement Friday, Cook County State's Attorney Anita Alvarez defended bringing the charges and said her office plans to appeal to the Illinois Supreme Court.

Drew's case joins an increasingly complicated mix of court opinions, pending appeals and proposed legislation that could put enforcement of the law in limbo as thousands of protesters — many likely with electronic devices that could record police actions — descend on the city for the summits.

"I think this decision gives the cause more momentum," said Ed Yohnka, a spokesman for the American Civil Liberties Union in Chicago, which has a pending federal lawsuit against Alvarez over the issue. "But I don't think I would argue there is clarity yet."

Illinois' eavesdropping statute, one of the strictest in the nation, makes it a felony to record any conversation without the consent of all parties. It carries stiffer sentences — of up to 15 years in prison — if a police officer or court official is recorded without his or her knowledge.

The debate over the state law began to heat up last year with a series of high-profile cases. In August, a Cook County jury acquitted a woman who had been charged for recording Chicago police internal affairs investigators she believed were trying to dissuade her from filing a sexual harassment complaint against a patrol officer.

The next month, a judge in southeastern Illinois' Crawford County declared the law was unconstitutional in the case of a man accused of recording police and court officials without their consent. Prosecutors there have appealed, and Illinois Attorney General Lisa Madigan is scheduled to file a brief with the state Supreme Court later this month.

Perhaps most importantly, the 7th U.S. Circuit Court of Appeals could rule soon in a lawsuit by the ACLU against Alvarez that argues the law violates First Amendment rights. Months ago a three-judge panel of the Chicago court, including influential Judge Richard Posner, heard oral arguments, the final stage before a decision.

Depending on how the various rulings shake out, the entire issue could wind up before the U.S. Supreme Court at some point, according to legal experts and court watchers.

"Everybody is kind of waiting for everybody else," said Josh Kutnick, Drew's attorney. "But I think in the reasonably near future we are hopefully going to see all of these chips fall into place."

While the court cases wind their way through the legal system, a bill introduced by state Rep. Elaine Nekritz, D-Northbrook, seeks to modify the current law to make it legal for citizens to record law enforcement officers who are on duty and in public.

The bill cleared a House committee last month following a showdown between law enforcement opponents and supporters who want the law changed before the G-8 and NATO summits begin. Though it could go to a vote in the House this month, it remains up in the air if there is time for it to pass in both chambers and reach Gov. Pat Quinn's desk.

On Friday, Nekritz was encouraged that there appeared to be a growing consensus that the law needs to be changed, but "that doesn't always translate into votes," she said.

Chicago police Supt. Garry McCarthy has said he doesn't object to audio recording of police officers as they perform their public duties. After all, a key strategy for police at the summits will be to try to manage protests and prevent police brutality lawsuits by recording how officers treat demonstrators. "If the law is changed, it would make our lives a lot easier," McCarthy recently told the Tribune.

But other law-enforcement groups, including the Fraternal Order of Police, oppose easing recording restrictions, saying that would have a chilling effect on witnesses' coming forward to aid police and could create situations in which victims of crime are re-victimized by viral videos of their suffering.

With the current law under attack, one central Illinois prosecutor is opting simply to not enforce it. Earlier this week, McLean County State's Attorney Ron Dozier in Bloomington cited flaws in the statute when he dropped charges against a man accused of recording an officer during a traffic stop.

"I just did not want to be in the position of prosecuting this," Dozier told the Tribune on Friday. "It's just wrong to say someone should get a felony on their record for just recording what's happening in public."

Meanwhile, Christopher Drew will remain free on bond while his case is appealed.

"I'm pretty happy after 21/2 years of dealing with this," said Drew, 61. "It's a good decision."

Behind him, a small group of supporters held up their smartphones, the red lights blinking, recording every word.

jmeisner@tribune.com