Defensive medicine is how physicians protect themselves from lawsuits. Whether ordering extra and unnecessary tests or avoiding high-risk patients, these measures reduce the chance of physicians facing a malpractice lawsuit for a bad outcome or missed diagnosis. At least 75 percent of physicians practice defensive medicine at an annual cost estimated to be $650 billion per year.

Medicine is an inexact science. Diseases don’t always manifest as described in textbooks. What seems like indigestion could in reality be a heart attack. And vice versa. Diagnostic tests are expensive and certain tests carry their own risks. Financial barriers such as insurance restrictions, preauthorization, and paperwork add additional barriers so physicians make their best judgment based on the evidence in front of them and their experience. If their decision in the heat of the moment, based on the information at hand and their desire to provide the best possible care to their patient, turns out to be wrong, their life can be turned upside down by a medical malpractice lawsuit.

Compare being a physician to being a policeman. Threatening situations are even less predictable for policemen than for physicians. Human beings, particularly criminals, don’t behave in a rational or predictable manner. Incomplete information adds to the mix. Is that real or toy gun? Is the suspect waving a knife for show or is it directed at my throat? Just as in medicine, decisions must be made quickly and with incomplete or conflicting information. While serious injury or death can result from a wrong decision, in medicine, unlike in law enforcement, the physician won’t be shot dead if they make the wrong decision.

Six Baltimore police officers were indicted in connection with the death of Freddie Gray who died while in police custody after arrest. Did the police officers commit “police malpractice”? Did they deviate from the “standard of care” during the arrest and detention process? Who knows? Baltimore State’s Attorney Marilyn Mosby, before any investigation of the facts and circumstances, saw that they were indicted. A trial awaits the policemen, but meanwhile their lives are ruined, professionally and financially.

Move west to Ferguson, Missouri where police officer Darren Wilson had his life turned upside down after shooting the "gentle giant" Michael Brown. The “hands up don’t shoot” meme, perpetuated by the media, politicians, and athletes turned out to be a lie. Although accused of police malpractice, Officer Wilson actually did adhere to the “standard of care” of policing.

President Obama has also joined the knee-jerk chorus of blaming the police before knowing any facts. In 2009 he claimed Cambridge, Massachusetts police “acted stupidly” in arresting a Harvard professor. Yet the president acknowledged, "I don't know, not having been there and not seeing all the facts, what role race played."

What’s a cop to do? While he can’t order extra tests, he can avoid the “high risk” patients as physicians do. If he observes criminal activity, he can look the other way or take his time responding until the crime is over. The result is defensive law enforcement. And like defensive medicine, it is on the rise.

Predictably, arrests are down. In Baltimore, “Police are booking fewer than half the number of people they pulled off the streets last year.” Crime is up and the police are nowhere to be seen. “May 2015 is already the deadliest month in 15 years” in Baltimore as police are playing defense. As one Baltimore resident described, “Before it was over-policing. Now there’s no police.”

Ditto in New York City, where arrests and tickets are also on the decline. Remember Eric Garner who died during his arrest in Staten Island? And the reaction of Mayor de Blasio, throwing the cops under the bus based on the “dangers” they pose? Yet despite all the accusations, the cops were cleared of any wrongdoing. The police, knowing they don’t have the support of their boss when they do their job and try to enforce the law, will stop enforcing the law. Hence the drop in arrests.

Medicine and law enforcement are inexact sciences. The vast majority of physicians and police officers are dedicated to their professions and strive to do their best, often under challenging circumstances. Incomplete or conflicting information means they make judgment calls. Usually correct but sometimes not. And when the wrong call is made, physicians face a malpractice lawsuit and police face indictment and prison.

The natural response is to avoid the high-risk situations. Stop accepting new patients, particularly sick patients with a greater chance of complications. Order extra tests to avoid missing a diagnosis, however unlikely. For police, just look the other way. Take your time responding to a distress call. Don’t make the arrest. And watch the crime rate climb.

Brian C Joondeph, MD, MPS, a Denver based physician and writer. Twitter @retinaldoctor.