Five people say they tried to explain their arrest was a mistake but Denver police didn't want to hear it. Now they're suing.The claim that "I didn't do it" is something police hear quite often, but the American Civil Liberties Union believes these five cases are different."In every case, the police had to ignore facts that demonstrated that they were arresting the wrong person," said ACLU Legal Director Mark Silverstein.Dennis Smith, a Denver Public Schools teacher, said he'd had problems as far back as 1989 with another man with the same name."There's another Dennis Smith in the world and he and I share the same birthday," Dennis Smith said.He had already obtained a letter from the Colorado Bureau of Investigation stating that this mix-up had occurred before. He said he offered three times to get that letter, out in his car, as Denver County sheriff's deputies were arresting him as he came to visit a Sudanese student at the county jail in January.Smith lost a few hours clearing it all up.Jose Ibarra said he was behind bars for 26 days."Being there is bad," Ibarra said.His family members had repeatedly tried to explain that he wasn't the Jose Cayetano Ibarra listed in the arrest warrant. Jose Ernesto Ibarra doesn't resemble the suspect at all, according to his mother-in-law."Because it doesn't even look like him. He's thin. He's ... I don't know if it's white, but he's lighter (skinned) than him," Carmen Mendoza said.Beyond the allegedly mistaken arrest, the ACLU said the five plaintiffs in the lawsuit also lost due process rights."They were deprived in that manner of an opportunity tell the judge, 'I'm not the person in that warrant,'" Silverstein said.Silverstein said the ACLU has found no clear police procedure for verifying a disputed arrest and are seeking monetary damages."There are systemic administration failures on the part of Denver's top policy-making officials to make sure that this doesn't happen. Or to make sure that if it happens, it's detected and fixed as soon as possible," Silverstein said. "And I just don't know, this might happen in Denver and in other jurisdictions."A Denver police spokesman and the city attorney had no comment on the pending litigation.