Juries in Michigan have wrestled with that question in recent weeks, as they grappled with the aftermath of a shooting at Oxford High School in Michigan that killed four children on November 30, 2021.

And in each parent’s case, the jury returned a clear answer: Yes. Despite being tried separately, both Jennifer and James Crumbley were found guilty of involuntary manslaughter in relation to their son Ethan’s actions.

It was a historic verdict. Never before had a parent in the US been found criminally responsible for manslaughter after their child committed a mass shooting.

On Tuesday, a sentencing hearing will decide where they face a maximum penalty of up to 15 years in prison.

But those who cheered the outcome — and those who warned against the legal precedent it set — have said the Crumbley cases will likely reverberate for years to come.

“You have a painful crime. You have a legal novelty and an unprecedented action. And then you have this social thing in which we’re all interested, all coming together in one case,” Ekow Yankah, a law professor at the University of Michigan, told Al Jazeera.

“And I think there’s this kind of deep intuition about: At what point are your children’s actions not your own?”

For weeks during the trials, prosecutors in Michigan painted a damning portrait of the Crumbleys as parents who zoomed past red flags ahead of their son’s deadly attack at Oxford High School.

Not only did they fail to secure the firearms in their home, but they also did not pursue “reasonable care” to prevent their son from engaging in harmful acts, prosecutors said.

Four days before the attack, James Crumbley bought the gun that his son, then 15 years old, would use in the murders. Prosecutors highlighted several indications that Ethan was experiencing severe mental health issues at the time, including hearing voices.

On the day of the shooting, the parents were called to the school after their son drew threatening pictures in class, but they did not notify administrators they had recently purchased a gun, nor did they take Ethan home.

Later that day, the teenager went to the restroom and returned brandishing the semi-automatic handgun.

The Crumbleys are not the first parents to face criminal prosecution after their teenage son committed a mass shooting, though.

After 19-year-old Robert Crimo III fatally shot seven people at a Fourth of July parade in suburban Chicago in 2022, his father, Robert Crimo Jr, initially faced seven felony counts of reckless conduct.

Prosecutors said the elder Crimo helped his son acquire the guns he used, despite being warned that the 19-year-old may pose a public safety risk.

In November of last year, however, the elder Crimo pleaded guilty to lesser misdemeanour charges as part of a deal with prosecutors.

Still, prominent gun control advocates and organisations say verdicts like those against Crimo and the Crumbleys could have a deterrent effect, helping to prevent future mass shootings.

Nicholas Suplina, the senior vice president for law and policy at Everytown for Gun Safety, said the convictions could serve as a warning about safely securing guns.

He noted a recent study that found three-fourths of school shooters acquired the firearm they used in their attack at home.

Some states also have laws requiring gun owners to keep their firearms away from children. Michigan, for example, has a “safe storage” law that requires guns to be secured if a minor is present.

“These verdicts send a clear message: first, that secure responsible firearm storage can save lives,” Suplina said in a video posted on social media in March.

“And second, that there will be accountability where people fail to act responsibly. Hopefully, it will help prevent future tragedies.”

Social message vs legal precedent

But Yankah, the University of Michigan professor, explained that the reaction within the legal community has been split, with some fearing the Crumbley verdict may forge a precedent with wide-ranging implications.

“One might think that with such a painful and unlikely event — and the way prosecution treated [the Crumbleys] as such remarkably negligent parents — that we just wouldn’t see a case like this again,” he said.

“But I do think the thing that worries legal experts is: We know that law lives in precedent, and once you have a precedent, it’s the most natural instinct for a prosecutor to use that precedent,” he said.

Evan Bernick, a professor at Northern Illinois University College of Law, has been among those warning of what the convictions could portend.

“There’s a saying: ‘Hard cases make bad law,’ which means that there’s always an initial horrifying case that’s used to justify the expansion of criminal law,” he told Al Jazeera. “Then there are a whole class of cases that you don’t see that you don’t get national intention.”

Both Bernick and Yankah pointed to the possibility of the precedent being gradually applied in lower-profile situations, particularly as a tool for prosecutors to pressure suspects into plea bargains. Marginalised communities could be particularly at risk, Bernick said.

“I don’t have a lot of confidence in the exercise of prosecutorial discretion to pick and choose only cases like this,” he said. “Once you’ve got a hammer — and this is definitely a hammer — everything can look like a nail, and people aren’t necessarily focused on how you’re wielding it.”

‘Very large gap’

The details of the Crumbley case may be distinctly modern, but contemplating the limits of parental accountability is an ancient tradition. The millennias-old question also has deep roots in US law.

“There are lots of instances throughout history and across cultures that certainly tie parents’ behaviours to children’s behaviours,” Eve Brank, a psychology professor at the University of Nebraska-Lincoln who studies parental responsibility laws, told Al Jazeera.

The works of the Greek poet Homer examined parental responsibility, she said. So too does the Biblical Book of Proverbs and the Code of Hammurabi, a Babylonian legal text from the 18th century BC, to name a few.

The concept has made its way into US law in three main areas, Brank explained. In 1846, Hawaii passed a law that allowed parents to be held civilly liable for their children’s actions. All states now a have version of that law.

In 1899, Colorado also established a law making “contributing to the delinquency of a minor” a crime. These laws were typically aimed at protecting a child from a parent or adult who enlisted them to do illegal activity, such as delivering drugs.

In the decades since, there have been a series of state laws that hold parents criminally responsible for children’s actions — typically carrying misdemeanour charges or requiring parents to pay fees related to trials. Locally, some laws have gone further.

For instance, Vice President Kamala Harris, during her time as San Francisco district attorney from 2004 to 2011, oversaw a controversial truancy programme that carried misdemeanour penalties for parents whose children regularly missed school. It was widely criticised for disproportionately affecting low-income and minority residents.

Still, Brank said, there is “a very large gap” between the punishments for parents in past cases and the Crumbley case. She cautioned that there has not been research conducted to determine if punishing parents will indeed serve as a deterrent for others.

“I think there are some assumptions that are being made in those ideas that we just don’t have empirical evidence to back up at this point,” she said.

“I think [this case] still begs the question whether this will give us the result we want,” she added. “So I still would advocate for more empirical research on the topic.”