In the London district of Havering, the scene around the four local schools was, just months ago, akin to a zoo . “It was absolutely murder around here. Cars everywhere–there was bound to be a serious accident or worse,” local mother Julie Picton told the Evening Standard .

The concern was that cars swarming by the schools to drop off kids were clogging the roads and blocking driveways, creating unsafe conditions for kids and parents who approached the schools on foot. The Havering council took note and has now made the practice a criminal offense: Parents who drop off or pick up their kids by car will be fined £100 ($123). If they fail to pay within two weeks, that fine increases tenfold, and the target parent may get a criminal record. This radical measure was put into practice in November 2016.

It’s possible for a district to implement this rule because an ordinance passed in 2014 allowed for the creation of Public Space Protection Orders (PSPOs), which ban certain behaviors from specific places, even though those behaviors aren’t themselves illegal. Some other PSPOs have, for instance, made walking a dog without a leash a punishable offense and criminalized loud drivers. These ordinances tend to be very polarizing.

In the case of Havering, the order made a difference in the first week. “More children are now walking to school,” said Councillor Jason Frost, lead cabinet member for the PSPO scheme, in a statement after the launch. “I am very hopeful that the PSPO schemes that will be implemented in other schools around the borough will be just as successful.”

The ban applies in designated zones around four schools for an hour and a half in the morning and in the afternoon. Taxis and rentals cars are subject to the ordinance, but anyone not dropping off or picking up kids is exempt. Enforcement is done by camera surveillance, and by a beat cop.

Predictably, some parents are furious. “It’s a sledgehammer to crack a nut,” Angie Baillieul told the Evening Standard. At one of the schools, in Engayne, the nearest practical drop-off point is now a five-minute walk from the school itself. Imagine having to walk for five whole minutes every morning and afternoon. It’s inhuman. Joking aside, some parents now have to circle the block looking for an actual parking space, instead of just letting their kids out quickly and driving away.

Yet the parents are the ones who brought the law upon themselves. The new scheme comes after “years of unsuccessful campaigns to encourage sensible driving and parking outside schools,” reports the Evening Standard, “which saw a small but determined minority continue to park dangerously, putting the lives of children at risk.”