Do you set the parking brake every time you get out of the car? If not, you're breaking the law.

It's a little-known law, but it's one that a Trophy Club family found out about the hard way in the Denton County section of Fort Worth.

"I thought it was a joke," Sue Johnston said. "I thought, 'Who gets a violation for a parking brake?'"

But her son got a Fort Worth parking ticket in late August citing "parking on city street without parking brake."

"I thought it was a joke, so I didn't pay it," she said. "And then I get a notice that I have a delinquent violation and now I owe them $55 instead of $30 that it originally was."

The Johnstons later learned that seven or eight cars got tickets for the same violation on Saturday, Aug. 24 at 1:51 a.m.

The citations were issued while several teens attended a birthday party at a home in the Chadwick Farms neighborhood of Fort Worth near Texas Motor Speedway in Denton County.

"They have flashlights -- I get that -- but it was dark outside," Johnston said. "How do you not know he doesn't have the parking brake on? I respect the police; I respect what they do. I'm the first one to stand up and be accountable for my actions, but I didn't know there was a law. I don't think anyone knows there's a law."

But there has been a law since 1995 that requires Texas drivers to set their parking brakes every time they leave their vehicle.

§ 545.404. UNATTENDED MOTOR VEHICLE. An operator may not leave the vehicle unattended without: stopping the engine; locking the ignition; removing the key from the ignition; setting the parking brake effectively; and if standing on a grade, turning the front wheels to the curb or side of the highway.

Fort Worth Police Cpl. Tracey Knight says it may be an obscure law, but officers can and will enforce all laws. While the circumstances of the ticket weren't immediately available, the officer who wrote the tickets likely was called for loud noise coming from the party. If officers cannot solve an issue directly, such as the noise complaint, they will try to reduce the likelihood of that problem occurring again by enforcing all appropriate laws.

Knight also said that someone who believes they've been wrongfully ticketed can challenge it in court.

In this case, two of those ticketed have successfully done so, Johnston said.

"They got it dismissed for lack of evidence, but I don't have the time to do that, and I shouldn't have to," she said. "It's not a violation that was harming anyone."

Johnston said she was told it would require two appearances at the Fort Worth Municipal Court near City Hall in downtown to fight the ticket. She said she can't afford to take two days off of work to do that.

As for how an officer can tell whether a parking brake has been set, Knight said it's relatively easy. If the emergency brake is in the center dash of a vehicle, you can tell whether it is up or down. And in the case of brakes under the dash, you can also tell if they've been depressed or not, she said.