This much you already know: Political campaigns can be costly. And that’s especially true for one candidate who ran for Chicago alderman last year.

John Garrido lost after getting knocked around by negative ads. He sued for defamation, and the outcome could end up costing him - personally - more than $150,000.

Garrido is a Chicago police lieutenant, a part-time attorney and - in recent years - an aspiring politician. Last year, he ran for alderman in the 45th Ward on the city’s far Northwest Side.

“I don’t want to say that I thought it was mine,” Garrido said in an interview last week at his law office. “But we definitely were doing very well and I thought we were going to be victorious.”

Garrido’s confidence wasn’t misplaced. He was well known and ran a high-energy - though relatively-low cost - campaign.

But in the end, “Well, it was a nail-biter. Came right down to the wire,” he said.

Thirty votes separated Garrido from his opponent.

“Absolutely crazy,” he said. “I believe one paper wrote that it was the second-closest race in the history of Chicago.”

If that’s so (and a spokesman from the Chicago Board of Election Commissioners doubts it), Garrido was on the losing side of history.

“Trust me, the second guessing. You know, when I stopped for dinner on a certain day, I could have walked an extra two blocks,” Garrido said. “I mean, yeah, of course you definitely second guess yourself all the way ‘til the end there.”

The winner was John Arena, who owns a graphic design business. Arena had won the bulk of labor union support in the race. The Service Employees International Union (SEIU) of Illinois, alone spent several hundred thousand dollars on this single ward race.

Garrido was hit over and over again with negative ads - many tying him to the unpopular deal to lease Chicago’s parking meters to a private company, a deal that’s led to increasingly higher parking rates.

“When Chicago privatized parking meters, our neighborhoods and working families got hurt,” boomed the voice-over on a SEIU TV ad. “Garrido even took cash from a corporation making millions from the parking meter deal.”

A sentence flashed on the screen: “Garrido took cash from parking meter company.”

“Absolutely false. Absolutely false,” Garrido said of the charge.

Well, maybe not “absolutely” false, but not quite as advertised. It turns out Garrido took money from the owner of a security firm working with the parking meter company. The claim was repeated in mailings to 45th Ward residents, along with other negative charges.

Just 10 days after he lost the election, Garrido filed a defamation lawsuit.

“My reputation was damaged,” he said. “My career’s been based on honesty and integrity. And they spent a lot of money to damage that. And unfortunately, there are very few ways that you can get recourse.”

He sued SEIU Illinois and other unions that sent out negative ads: Chicago Federation of Labor and UNITE HERE Local 1, as well as Comcast, which aired the TV ad, and the winning candidate, John Arena, whose campaign also made the parking meter claim.

Arena said in an interview last week that Garrido should’ve known better than to accept a donation at all connected to the parking meter deal.

“You don’t want to be 10 feet from that. You don’t want to be 100 miles from that deal if you’re in a campaign running,” Arena said. “If that were me, I would have returned the money. I wouldn’t want to have anything to do with that deal in the context of that race.”

Besides, Arena said, hits happen in the course of an election; if you can’t take them, don’t play the game.

“It comes off…as sour grapes that you ran a campaign,” Arena said. “You win or you lose, and you have to decide whether you’re going to come back and run again the next time or file a lawsuit that wastes a lot of people’s time.”

Representatives for SEIU Illinois, Chicago Federation of Labor, UNITE HERE Local 1 and Comcast all declined to comment for this story, each noting the pending lawsuit.

So far, it hasn’t mattered if the parking meter claim was true, somewhat true or not at all true. The defamation suit was dismissed before its merits were ever discussed, because of an Illinois law passed in 2007: the Citizen Participation Act.

Supporters of the legislation wanted to discourage lawsuits that could have a “chill[ing]” effect on people wanting to speak out in public forums. Basically, the law said you can’t be sued for what you say, if you’re legitimately trying to influence “government action.”

“So that people can’t use the courts as a means of litigating their political fights,” explains Shari Albrecht, an attorney at the Chicago law firm Mandell Menkes. She’s represented a handful of defendants in lawsuits where the Citizen Participation Act is invoked.

“The defendant doesn’t have to go to the effort of trying to prove, for instance, that their statements were true, or that for whatever other reason it wasn’t defamation. All the defendant has to do is show that the Citizen Participation Act applies,” Albrecht said.

And then the lawsuit is dismissed. Plus, the plaintiff - the person claiming to be defamed - has to pay a chunk of the other side’s legal bills.

And that’s what John Garrido is looking at, according to court documents: $13,164 for lawyers hired by the Chicago Federation of Labor, $34,149 for SEIU Illinois, $34,222 for UNITE HERE Local 1, $62,407 for Comcast and $17,097 for John Arena. All told, those defendants say Garrido owes them roughly $161,000.

In his order last week re-affirming his dismissal of the case, Cook County Judge Michael Panter wrote that courts shouldn’t “police the veracity of our political candidates’ campaign allegations.”

Garrido plans to appeal.

“The statute that they’re using to try to dismiss the case, in my opinion, wasn’t created to protect speech that’s untrue. You don’t just get, you know, free pass to lie just because it’s during a campaign,” Garrido said.

“Everybody’s got the opinion that, well - you know - politics, you’ve got to have a thick skin. It’s rough and tumble. This is Chicago politics. And that’s fine and I’m good with that,” Garrido said. “Nobody’s got a thicker skin than a Chicago police officer. But there has to be a line somewhere that you cannot cross.”

And Judge Panter at least appears somewhat sympathetic to Garrido’s argument, calling attention in his ruling a “fundamental irony” with the Citizen Protection Act.

The law, he wrote, “closes the door on one very important right to participate in government, applying to the courts for relief from injury…in the name of protecting another right to participate in government, like here, running for political office.”

Panter pleaded for “clarification,” and he could get it soon. In September, the Illinois Supreme Court heard a case questioning whether such a broad protection of public statements in constitutional. The justices have not yet ruled.