When the police test a substance for drugs while out in the field, you'd assume they'd have top-of-the-line equipment that's nearly 100 percent accurate. Well, it turns out that assumption would be wrong, and it can get a lot of people in deep trouble.

Last May, Michael McCarron was making a delivery to an Air Force base in Colorado. After security inspected his vehicle, they detained McCarron and ran a field sobriety test which involves the person looking at a 45 degree angle while officers examine their eyes. McCarron supposedly failed this highly subjective test. Colorado police were called to the base, and McCarron was given another sobriety test which he passed. But despite that, he was still detained by the police.

Turns out security had found marijuana inside McCarron's vehicle. The police ran two Narcotics Identification Tests that both found that McCarron's marijuana contained methamphetamine. McCarron wound up getting arrested for possession of meth.

Narcotics Identification Tests are notoriously unreliable. They are similar to portable breathalyzers for alcohol, and often report false positives. In fact, Narcotics Identification Tests results are not admissible in court due to their unreliable results.

Turns out they were unreliable in McCarron's case as well. The Colorado Springs Metro Crime Laboratory tested McCarron's marijuana and found no traces of meth. This led to the police dropping charges against McCarron.

But just because he's been spared from jail time doesn't mean the incident hasn't negatively affected McCarron. He lost his delivery job due to the charges, lost the respect of his friends and had to spend thousands of dollars on an attorney for the case. Also, even though the charges were dropped, his record still contains the felony arrest for the incident, which could hurt his future job prospects.

So the police can ruin a man's life using an unreliable test and then get away unpunished when it turns out they were wrong. That's criminal justice in America.