Jay Street in downtown Brooklyn is one of the most important segments in the city’s bike network, the key passage to and from the Manhattan Bridge. It’s also a huge impediment to biking in the city — the street is rife with double-parking, illegal U-turns, and the unnerving threat of a car door suddenly opening and throwing you into the path of a passing bus. An upcoming redesign of Jay Street should improve the situation, but it too will be hampered by the culture of parking placard abuse that pervades downtown Brooklyn streets.

The chaos on Jay Street emanates from placard holders and fake placard holders who park all over the place. Even legit placards aren’t a valid license to park in bus stops or crosswalks, but NYPD doesn’t enforce the rules. Soon after the 84th Precinct cracked down on Jay Street placard abuse in 2014, the commanding officer was reassigned.

Advocates campaigned long and hard to get the city to redesign Jay Street, and this summer, DOT plans to flip the bike lane with the parking lane to provide some physical protection. It should be a less stressful experience, but there’s a catch: The proposed bike lane is a sub-standard width on a street that typically already sees 2,400 cyclists in the peak 12-hour period. The National Association of City Transportation Officials advises that protected lanes should be at least five feet wide with a three-foot buffer from parked cars to keep cyclists clear of the door zone, but the Jay Street design calls for five-foot lanes with two-foot buffers.

The bike lane could be wider if it weren’t for all the placard parking on Jay Street. Take out the parking, and there’s a lot more room to work with. If the city was willing to make placard holders park a little further from their destinations — like in one of the many nearby garages with a glut of parking, thanks to downtown Brooklyn’s parking requirements — the options for good street design open up.

So who is parking on Jay Street? Whose entitlement to convenient personal parking trumps street safety and good bus service for everyone? I made a few trips in the past week to document the placard abuse up close.

The root of the placard problem lies with the courts in downtown Brooklyn and the law enforcement agencies with business there. Most of the placards belonged to New York State court officers and employees of the Brooklyn District Attorney, whose offices are on Jay Street. Like placard abuse throughout NYC, the problem speaks to the inability and unwillingness of the law enforcement establishment to police itself for the public’s benefit.

All sorts of other cars are, of course, also parked illegally or idling all along Jay Street, and anyone with some sort of government identification can get away with it. There are police officers idling in bike lanes and agency vehicles parked in bus stops all along Jay between Fulton Mall and Tillary Street. Illegal placard abuse gives cover to yet more law-breaking: A lot of idling drivers lined up in the bike lane behind police cars didn’t even have placards or placard-type devices.

Here’s a visual survey of the world of petty corruption on Jay Street — who’s parking with impunity and the tools they use to get away with it.

The most common parking placards on Jay Street belong to court officers and employees of Brooklyn DA Ken Thompson’s office…

Any sort of NYPD paraphernalia is good as gold on Jay Street…

Then there are various other government agency placards and markers of public employment that ward off any parking enforcement officers who might walk by…

Not affiliated with NYC government in any way? Not a problem…

Despite all that, someone must be patrolling Jay Street and keeping an eye out for naked dashboards, because I did find one car with a ticket: