There's A Reason Cops Lie In Court

But Ohio State law professor Michelle Alexander argues in a compelling New York Times op-ed cops aren't necessarily more trustworthy than the alleged criminals they're trying to put away.

To back up this basic argument, she points out that San Francisco's own former police commissioner called police officer perjury in court "commonplace."

Part of the problem is that cops have an incentive to lie under oath, Alexander says.

The Edward Byrne Memorial Justice Assistance Grant Program and other federal grants effectively encourage local law enforcement to boost drug arrests, according to Alexander. Agencies get cash if they arrest high numbers of people for drug offenses, she says.

New York Mayor Bloomberg has denied the existence of explicit arrest "quotas," but former officers have alleged quotas do exist in the Big Apple.

So, it's natural that cops might feel pressure to fudge testimony against drug suspects.

There's another reason cops might lie under oath, Alexander says. Cops are people, and many people lie every day.

A recent study presented at the American Psychological Association's 20th convention reveals Americans lie, on average, 11 times a week.

Research by MIT psychology professor Dan Ariely also suggests that people are more likely to cheat -- a form of lying -- if they're in the same room with someone who's clearly cheating.

For police departments, this could mean the culture of lying under oath is self-perpetuating.

This natural, human tendency to lie makes incentives like quotas all the more dangerous, according to Alexander.

As Alexander notes, "One lie can destroy a life."