We all lie. We all probably lie every day. It is baked into us. Humans are the only animals who lie. Even presidents lie.

Usually the results are benign. "I didn't get your email," or "No, really, that's a beautiful tie."

We don't have to think about consequences. But what if our lies could destroy a life, take away someone's freedom or put a person in danger? That's a different kind of lying.

That's the kind of fallout that can happen when the lie is told by a police officer.

We honour our law enforcement people as we should, for what they do.

We ask them to do the meanest of jobs while keeping us safe and punishing the villains. We hold them to a higher standard of probity than ordinary citizens.

And we insist they tell the truth. Especially when they are in the witness box.

Unfortunately there is a growing body of evidence to suggest that police often lie under oath to ensure convicting the accused.

In fact some cops have a name for it: "testilying." It's also called Blue Lies.

It's important to note that not every cop lies every time he or she testifies. But there are enough incidents here and in the United States that should raise concerns in law enforcement circles.

Police chiefs will admit that some police officers lie. But they insist it is simply a few rogue officers, the classic bad apples defence.

The incentive for cops to lie must be overwhelming, writes Michael Enright, but the consequences of lying could be potentially devastating.

In 2012, The Toronto Star published the results of an important survey the paper carried out looking at a number of trials between 2005 and 2012.

It found that police regularly make inconsistent or false statements while under oath. It also discovered that disciplinary actions, including charges of perjury, are rarely taken.

Cops lie for various reasons. In 2014 in Edmonton, a police officer was charged for lying under oath six separate times — in traffic court of all places.

In Calgary, in August of last year, three cops charged with using excessive force to execute an arrest, were accused of lying.

In Hamilton, in June 2016, an officer was convicted of lying and planting a weapon in a suspected drug trafficker's house.

Lying by police seems to be most common in drug prosecutions.

Having worked a case for weeks, sometimes months, the cops are naturally interested in getting a conviction.

They have assumed the accused is guilty. After all, drug dealers are notorious liars themselves. And often violent.

The police want to get them off the streets. The incentive to lie must be overwhelming. So they tailor their evidence in a way that would lead to a conviction.

The practice of routine fabrication by police in the courtroom can have three immediate and potentially devastating consequences.

In the first place, innocent people could lose their freedom.

Secondly, it could raise doubts in the public mind about the integrity of the criminal justice system. And finally, as more incidents of "testilying" become public, ordinary citizens could begin to lose confidence in their police departments.

Should that even begin to happen, our system of law enforcement could be irreparably damaged.

Click 'listen' above to hear the essay.