BINGHAMTON, N.Y. – Zulayka McKinstry’s once silly, sociable daughter has stopped seeing friends, talking to siblings and trusting anyone — changes McKinstry dates to the day in January 2019 when her daughter’s school principal decided that “hyper and giddy” were suspicious behaviors in a 12-year-old girl.

McKinstry’s daughter was sent to the nurse’s office and forced to undress so that she could be searched for contraband that did not exist.

“It’s not fair that now I have to say, ‘It’s OK to be Black and hyper and giddy,’ that it’s not a crime to smile,” she said. “And she doesn’t believe me.”

The Binghamton, N.Y., case is now the subject of what might be a groundbreaking federal lawsuit by the NAACP Legal Defense and Educational Fund, which has drawn on the disparate treatment and discipline rates of Black girls to pursue it.

The disproportionate discipline rates of Black boys have long dominated discussions about the harmful effects of punitive discipline policies, but recent high-profile cases have begun to reframe the debate around the plight of Black girls.

Statistically, Black boys have led the country in suspensions, expulsions and school arrests. But Black girls’ discipline rates are not far behind those of Black boys, and in several categories, such as suspensions and law enforcement referrals, the disparities between Black and white girls eclipse those between Black and white boys.

A New York Times analysis of the most recent discipline data from the Education Department found that Black girls are more than five times more likely than white girls to be suspended at least once from school, seven times more likely to receive multiple out-of-school suspensions than white girls and three times more likely to receive referrals to law enforcement.

In New York City, Black girls in elementary and middle school were about 11 times more likely to be suspended than their white peers in 2017, said a report from the Education Trust-New York, a research and advocacy group. In Iowa, Black girls were nine times more likely to be arrested at school than white girls, said an analysis by the American Civil Liberties Union.

The disproportionate discipline rates indicate what researchers have long said: It is not that Black children misbehave more than their peers, but their behaviors may be judged more harshly. Black girls are viewed by educators as more suspicious, mature, provocative and aggressive than their white peers, said Rebecca Epstein, executive director of the Georgetown Law Center on Poverty and Inequality.

The Binghamton lawsuit, filed by the NAACP Legal Defense and Educational Fund last year against the Binghamton City School District, will test whether such studies can translate into legal recourse. The organization argued that administrators “were motivated by false race- and gender-based stereotypes in directing, facilitating and conducting these unlawful searches” on McKinstry’s daughter and three other 12-year-old Black girls. The school nurse who conducted the searches called the girls “loud, disrespectful and having ‘attitudes,’ ” the complaint said. It accused the nurse of commenting that the breasts of one of the girls were unusually large for her age and of invoking the “stereotypical view of Black girls as older and more mature than white girls of similar age.”

“This case is about the criminalization of Black childhood,” said Cara McClellan, a lawyer who is representing the girls.

Shannon O’Connor, lawyer for the Binghamton City School District, maintained its position that the four girls “presented symptoms that suggested the school nurse should provide a standard health and safety check” and that they were not strip-searched. She said the girls were cleared without “incident, complaint or discipline of any kind.”

LaTasha DeLoach has been working for years through Iowa-based organizations G!World and Sankofa Outreach Connection to dismantle the perception that Black girls are not as endangered by systemic racism as boys. “These are slave narratives,” she said. “Black men were publicly hanged, while Black women were raped in secret. This tendency to hide Black women’s pain dates back years.”

The Binghamton case spurred protests and petitions, but the girls — now 14 and starting high school — see no justice. “Justice would be for people to know what we go through now and for this never to happen to another African American female,” said McKinstry’s daughter.

A state investigation ordered by Gov. Andrew Cuomo produced a report that listed the district’s policies, including its strip-search policy, but did not address the girls’ case. The New York State Police Department said its investigation was closed without charges.