Matthias Manz isn't sure what to do. The Original Northwood resident's family received four speed camera tickets in the past three years and coughed up the $40 fine each time, trusting that the government wouldn't issue bogus citations. Now, with the revelation that some cameras have issued more than 5 percent of their tickets in error, Manz is wishing he hadn't been so quick to pay.

"I should have challenged these tickets," said Manz, 58, a retired federal worker. "I paid them only because I didn't know what to do."

It's a quandary that affects drivers throughout the city and the surrounding area. Baltimore officials have acknowledged issuing at least 350 tickets in error, while the cameras' professed error rates suggest that many more have not been identified.

Legal experts say motorists like Manz can ask the courts to reopen their speed camera cases, even if they've already paid. Some prominent attorneys in the city, meanwhile, say they are pondering a class action lawsuit on behalf of all aggrieved drivers.

Manz says he wants Baltimore officials to go back through the thousands of tickets issued themselves, audit them, and refund those from residents improperly cited.

"That's only fair," he said. "People were being charged for things when they weren't at fault. The city owes it to us as citizens to go back and check these things out."

When reports of problems with the cameras first arose, city transportation officials promised to issue refunds to "affected" drivers, though they haven't said who that might be.

In the meantime, local legal experts said, the driving public needs to consider how much trouble they want to go through for a $40 speeding ticket.

Colin Starger, an assistant law professor at the University of Baltimore who has worked with the Innocence Project, said people interested in challenging their tickets should marshal as much evidence on their side as possible. The question then becomes whether fighting the ticket is really worth it.

"Basically the only reason to do it would be if you wanted to get $40 back and stick it to the man," Starger said.

Officials with the city's speed camera contractor, Xerox State & Local Solutions, told a mayoral task force studying the city's program that a recent review of the city's 83 cameras found five that have been issuing one erroneous citation for each 20 they put out. Those five cameras have been idled and are no longer issuing tickets. Combined, the five cameras have generated at least 15,000 tickets, city records show, translating to $600,000 in potential fines for motorists.

Xerox, which is paid a portion of each fine that the cameras collect, said its review did not find similar problems with the city's other cameras, which remain in operation. The General Assembly, the mayor's office and the City Council have all pledged to investigate the speed camera system and correct problems.

Khalil A. Zaied, the city's transportation director, said he planned to hire a private engineering firm to study the city's cameras. He said about 350 erroneous tickets uncovered during Xerox's internal audit, which looked at a sampling of about 7,000 tickets, would be voided or refunded. City officials have declined to conduct an audit of all speed camera tickets.

Manz said he doesn't hold out much hope for a favorable resolution.

"I do feel like I don't have any legal remedies left. I suppose that since I paid them, that's technically the end of it," he said. "What they've done is priced these at $40, right where most people think it's too small to bother fighting it."

For that reason, Starger described the cameras as "a brilliantly conceived system of nuisance." And Bruce Godfrey, a traffic attorney in Reisterstown, said he gets lots of calls about the speed camera tickets, but they never lead to any business because it does not make financial sense for him to take on the case.

"Even if you win, you lose," he said.

Another option, attorneys say, would be to pursue a class action suit arguing that the system is on shaky legal footing because contractors are paid for each ticket they issue, and that the cameras are generally unreliable. If large numbers of tickets were thrown out, the payday might be big enough to attract a plucky lawyer.

"If [the cameras are] biased, you've got at least a due-process issue," said Robert Lande, a law professor at the University of Baltimore. "I think that just colors everything."

Legal experts said a successful case could lead to thousands of tickets being thrown out — even those already paid — and would force the city to sharpen up the way its system is run. They also cautioned that mounting a successful challenge in the courts would be expensive and time-consuming and face many hurdles.