Family, friends and demonstrators gather in a parking lot in Clearwater, Fla., where Markeis McGlockton was shot and killed in an altercation last month. (Luis Santana/AP)

THE SURVEILLANCE video from the parking lot of the Circle A in Clearwater, Fla., leaves little to the imagination: Britany Jacobs and two of her children were waiting in a car for her boyfriend, Markeis McGlockton, and their 5-year-old son to return from a snack run last month. Another man, identified as Michael Drejka, approached the car and began to berate Ms. Jacobs for parking in a handicap spot. Hearing the commotion, Mr. McGlockton emerged from the store and shoved Mr. Drejka to the ground. He had just taken a step away when Mr. Drejka pulled out a gun and shot him in the chest. Mr. McGlockton then ran into the convenience store, where he bled to death as his 5-year-old son stood screaming beside him.

There is no question that Mr. Drejka fired the killing shot. Yet a day later, Pinellas County Sheriff Bob Gualtieri announced that — thanks to Florida’s “stand your ground” law — Mr. Drejka would not be arrested. Under the law, anyone who “reasonably believes” that deadly force is necessary “to prevent imminent death or great bodily harm” does not have a duty to retreat. Florida’s law operates wherever people have a legal right to be — in their homes, at work or in any public space — and places the burden of proof squarely on the prosecutor , making it one of the most extreme versions of the law in the country.

As experts have pointed out, the “stand your ground” defense might not apply in Mr. Drejka’s case: The video footage clearly shows Mr. McGlockton backing away when he was shot, and Florida prosecutors are reviewing the case to determine if charges should be filed. That should be given serious consideration. But Mr. Gualtieri’s decision not to arrest Mr. Drejka highlights the many problems with these laws, which are on the books in 25 states . By creating a more lax standard for the use of lethal force, the laws excuse and perhaps incentivize reckless violence.

Supporters of the laws argue that they make communities safer. In fact, mounting evidence suggests just the opposite. A 2016 article in Epidemiologic Reviews found that “stand your ground” laws are correlated with higher homicide rates. Similarly, a Rand Corp. review found “moderate evidence” that the laws result in increased rates of homicide. Because perceptions of risk are often based on biases, these laws can also exacerbate racial disparities in criminal justice: A 2015 study examining Florida’s law found that it had a “quantifiable racial bias,” with higher conviction rates in cases with white victims compared with those with nonwhite victims. It may not just be a coincidence in this case that the shooter is white and the victim African American.

More than six years after George Zimmerman shot and killed Trayvon Martin in Sanford, Fla., this tragic incident has brought national attention to the issue yet again. There are growing movements in multiple states to amend or repeal “stand your ground” laws. State legislatures should reinstate the duty to retreat before more people are endangered by laws that tell people to shoot first and think later.