New York City’s Vision Zero efforts aimed at protecting pedestrians has some union officials upset.

Last week, thanks to a failure-to-yield law that went into effect in August, a bus driver was arrested for striking and severely injuring a 15-year-old girl. The Transportation Workers Union 100 then sent a memo to its members warning that bus drivers were under attack and being treated like criminals.

The union says that the arrest was unjust, and has supported an amendment to exclude bus drivers from the law. But proponents of Vision Zero say that bus drivers should be an example for other drivers, and that the punishment, fines up to $250 or 30 days in jail, is not excessive.

“The new failure-to-yield law is a vital tool in our efforts to protect pedestrians and make our streets safer,” a spokesman for the Mayor said in a statement on Thursday. “We will work with our partners at the MTA and push for the training and support drivers need to do their job safely, and we are looking closely at changes we can make on our streets to prevent crashes between pedestrians and buses.”

In December, the MTA announced a pilot program for buses to sound warning messages to pedestrians at intersections, but critics of these kinds of efforts say they blame pedestrians for drivers’ carelessness.

The Times reports that the union has taken its fight to social media.

The union created a hashtag — #LetsBePerfect — for its 10,000 bus operators, protesting that … Vision Zero … unreasonably demanded perfection.

A quick look at that tag shows, as you might expect, people co-opting the phrase.

#LetsBePerfect and stiffen penalties for drivers including @TWULocal100 members who harm pedestrians. Aggressive prosecution & no leniency.

— Peter Feld (@peterfeld) February 20, 2015