In her July 29 column on the proposed Montgomery County curfew, Petula Dvorak asked: “So, how exactly do they [the police] plan on telling the good kids from the bad ones?” As the police officer she quoted in the column, I judge it’s my duty to answer.

I understand that some cops of yesteryear judged a “book by its cover.” The good news is today’s Montgomery County police are part of one of the first generations of Americans to have grown up “color blind,” or for that matter, blind to all bias. They’ll judge these kids based on something else, something they have learned quickly on this job.

They won’t be judging the kids out on a date, or the kids shooting baskets at the rec center or swing dancing in Cabin John. It won’t be the kids watching movies or eating at Lebanese Taverna, or those ice skating in the winter. And it won’t be the kids at the skateboard park, the ones watching a high school football game, or those coming from a Friday night religious meeting.

We are able to tell the bad kids based on their behavior. It’s the kids who come to hang out but never spend a dime at area businesses. The ones dropping the “F-bomb” so loud that you cringe when you’re walking by with your family. The ones who comment on the appearance of your daughters, walking behind them and taunting with comments so crude it would make a sailor blush. The ones who end up staying late, wanting to fistfight kids from other neighborhoods because of some street name or boundary line that is important only in their minds. The ones who follow you as you walk out of Silver Spring into the adjoining neighborhoods, snatching your iPhone and running to the Metro to get home. They’re the ones who take your loose change and your stereo from your unlocked car as it sits in the parking garage waiting for you and your family to finish your ice cream.

Petula Dvorak is right: If parents would impose their own curfews, the government wouldn’t need to. But the harsh reality is that some parents aren’t as capable, caring or willing as Dvorak or the activists are speaking out against this curfew. Identifying the bad kids is very simple, and they don’t need to wear an ID card for the police to figure it out. And the kids who are engaging in normal weekend night activities will not be the subjects of a teen witch hunt. This is only meant as a tool for the police to use to keep kids from getting in trouble (both as victims or as suspects), or to end trouble early when warnings to go home are not heeded.

And even if all I do is I take one bad kid off the street for one night, that’s one less opportunity, and one less victim, that he or she will be able to take advantage of in my community.

The writer is a deputy commander for the Silver Spring District of the Montgomery County Police Department.