According to an old lawyer joke, the best way to tell when a lawyer is lying is to look to see if his lips are moving. That rule seems to apply to cops on the witness stand, too. But “testilying” is no laughing matter. It is undoubtedly a significant factor in many wrongful convictions.
Proving it to the courts’ satisfaction, though, is another matter. As Radley Balko notes here, “The problem isn’t that cops aren’t capable of telling the truth. The problem is that the courts have treated cops as if they’re incapable of lying.”
Alan M. Dershowitz said the same thing in an op-ed in 1994. “Some judges refuse to close their eyes to perjury,” he wrote, “but they are the rare exception to the rule of blindness, deafness and muteness that guides the vast majority of judges and prosecutors.”
Balko argues that this could be changing, thanks to increasing prevalence of video cameras that catch cops in lies, as happened recently in a Chicago-area case. But until video cameras are everywhere, some cops will probably continue to lie as long as the courts allow them to get away with it.