For years, thousands of people who hadn’t been convicted of a crime languished in New York jails because they could not afford bail. New Yorkers were locked away for months, even years, not because they were dangerous, but because they were poor.

Lives were ruined. Young people, overwhelmingly black and Hispanic teenagers, were thrown away like trash. Families were splintered, and communities torn apart.

Finally last year, the State Legislature banned bail for defendants charged with most misdemeanor and nonviolent offenses. New York’s top Democrats preened and crowed, congratulating themselves as progressive champions.

Now, those same Democrats are buckling, crumpling in the face of an ugly campaign to undermine the bail law by forces long opposed to reform.

The effort to destroy bail reform was underway even before the law went into effect. Prosecutors and police unions issued ominous warnings about its imagined impact. One district attorney was even recorded training prosecutors in how to subvert the law.

It wasn’t until a spike in anti-Semitic hate crimes though, that the campaign really began to pick up steam. Some in the Hasidic community, an important voting bloc in New York, called on lawmakers to revisit the bail law. The New York Post, true to character, helped things along by telling the story of Tiffany Harris, a Brooklyn woman who allegedly slapped three Orthodox women and shouted an anti-Semitic slur, then was released without bail, only to be arrested the following day for allegedly punching a woman.

On Jan. 1, a judge ordered Ms. Harris held at a hospital to undergo a psychiatric evaluation. If anything, high-profile cases like this one should prompt calls for increased funding of the state’s supervised release programs, to ensure they are equipped to serve defendants fighting mental health or substance abuse issues. Roughly 40 percent of those locked up on Rikers Island are known to be suffering from mental illness — evidence of how New York has used its jails until now. But amid a deeply troubling rise in anti-Semitic hate crimes, the pressure is on to punish instead. So the Harris case, aided greatly by The New York Post, has led to calls for more incarceration.

“We need to make sure that habitual criminals stay behind bars — not on the streets,” Assemblyman Simcha Eichenstein wrote on Twitter on Dec. 30, two days before the bail law went into effect.

Never mind that bail is assessed in New York according to flight risk, not public safety. Never mind that Ms. Harris hadn’t been convicted of the crime. “It really is a vigilante mentality,” said Lisa Schreibersdorf‏, the executive director of Brooklyn Defender Services, which represents Ms. Harris.

Crime remains extremely low. Yet the same people are making the same tiresome arguments, calling for more police officers to save us from the criminals whom liberals allow to roam the streets.

Republican Party leaders in New York have promised to campaign on the issue, insisting without evidence that bail reforms will return New York to the early 1990s, when the murder rate was over 2,000 a year.

The Twitter feed of the Sergeants Benevolent Association is offering a steady stream of hysteria. “Law enforcement across NY State can NO longer keep violent prisoners in jail,” it wrote Jan. 2. “NYS residents need to beware and may no longer be safe.”

People who have never shown much interest in the enormous cost of overpolicing and mass incarceration, or in the lives of black and Hispanic Americans in general, assure us that the solution to every problem is to lock people away and throw away the key.

“The real solution to disorder in our cities is the same as it always has been: More and better policing,” Senator Tom Cotton said in a speech this month. “New York’s finest — and police officers all across the country — have broken crime waves in the past, using steely resolve and superior force. They can do it again, if only we give them the freedom and support they need.”

Disappointingly, the city’s police commissioner, Dermot Shea, has joined the voices opposed to the reforms.

In no time, most of the state’s top Democrats, feeling the pressure, have signaled that they are open to changing or scaling back the reforms, just days after they went into effect. That includes Gov. Andrew Cuomo; the Senate majority leader, Andrea Stewart-Cousins; State Attorney General Letitia James; and Brooklyn’s borough president, Eric Adams.

Mayor Bill de Blasio, though, has outdone himself, offering praise for the bail law out of one side of his mouth while also promoting a change that would allow judges to consider dangerousness when setting bail. New York has never had such a measure on the books. Studies have shown that such consideration are likely to worsen racial disparities already rampant in the criminal justice system.

Only the Assembly speaker, Carl Heastie, a longtime supporter of the bail reforms, has tried to hold the line, reminding the state why the changes were necessary in the first place. “For too long, our criminal justice system has allowed those with the means to grease the wheels of justice, leaving those without to languish,” he said in Albany on Thursday. “By implementing this system, everyone is treated the same.”

This was all so predictable. This is, after all, the United States, where outrage over a woman like Tiffany Harris, who is black, can undo years of hard-fought criminal justice reform, while no one bats an eyelash as Harvey Weinstein, accused of being a serial rapist, walks free on bail.

Democrats should grow a spine, stand up for the law and reassure the public that they are at no increased danger. To do that, they must ensure that jail is not the only answer to public safety. The governor, mayor and Legislature can devote more attention to the state’s supervised release programs and mental health system. As a temporary measure, they can send more police officers to Orthodox Jewish communities that have been targeted by anti-Semitism. But they should resist calls to dismantle the law, and especially reject allowing judges to consider “dangerousness,” a standard that would take New York back into the criminal justice Dark Ages.

For years, jail was the easy answer to issues arising from complicated problems of addiction, mental illness, poverty and shattered communities. To build a fairer criminal justice system, New York has already committed itself to a better way — all it needs now are leaders who share that commitment.