New Jersey is suing a national preschool chain over allegations that it discriminated against a 3-year-old girl with Down syndrome, when it tossed her out of classes, because she wasn't potty trained.

In a 17-page complaint filed in New Jersey Superior Court on Wednesday, authorities singled out Chesterbrook Academy in Moorestown, the former school of a girl identified in court records as "Jane." Jane was expelled after the state alleged she failed to meet an arbitrary toilet-training "deadline," while other students were held to different standards.

"The state's position is that Chesterbrook had a duty under the law to accommodate this 3-year-old girl – who had been enrolled there since infancy – and that doing so would not have been significantly burdensome or fundamentally disruptive to its services and programs," state Attorney General Christopher Porrino said in a news release. "The company's hardline corporate decision has harmed this child and her entire family."

According to the complaint, Jane was moved from a beginner to an intermediate-level class in January 2015 without any input from her family. The school's principal, who was newly-appointed, informed Jane's parents that "a corporate policy" required the toddler to be potty trained as part of the intermediate class.

Jane's parents responded with a note from the girl's physician that said that due to her Down syndrome, Jane was developmentally delayed. She is not expected to be fully potty trained until after she turns 5 years old.

Two days later, Jane's parents got another note from the principal warning them that Jane would be dis-enrolled if she failed to become potty trained "within seven days," according to the complaint.

Jane was kicked out of the school when she failed to meet that deadline, according to the Attorney General's Office. Meanwhile, "other, non-disabled intermediate students were allowed to remain despite needing changing assistance in connection with toileting," authorities said.

During a subsequent investigation by the attorney general's Division on Civil Rights, Chesterbrook officials claimed Jane was expelled not because of her delayed development but instead because "Jane had exhibited disruptive behavior."

"However, during the Division's investigation, Chesterbrook officials were only able to document two examples of such behavior," officials said in a news release.

Chesterbrook is part of the Nobel Learning Communities Inc. school chain, which operates elementary and preschools in 19 states. In New Jersey, the group operates seven schools, including the Chesterbrook facility.

"This case is particularly troubling, because Chesterbrook and its parent company have faced similar allegations in the past despite holding themselves out as the 'gold standard for ADA classroom compliance,'" Division on Civil Rights Director Craig Sashihara said.

Authorities pointed to multiple cases going back 10 years of alleged discrimination, including a 2009 Department of Justice lawsuit filed against Nobel Learning Centers and settled in 2011 with the promise that the system would "implement a disability non-discrimination policy," among other stipulations.

"Given their past assurances to comply with the law and to train their staff on the governing legal standards for dealing with young children with disabilities, we expected better -- more compliance, more sensitivity, and less intractability -- when responding to the needs of a 3-year-old girl with Down syndrome," Sashihara said.

In a statement released to NJ.com, a spokesman for Nobel Learning Communities Inc. declined to discuss the details of Jane's case due to the ongoing nature of the lawsuit.

"However, our schools are dedicated to serving the needs of a diverse student population, including many with disabilities," the statement said. "We are proud of our comprehensive policies and procedures to ensure compliance with state and federal laws governing the rights of all students."

Authorities are seeking compensatory and punitive damages and an agreement to allow the Division on Civil Rights to monitor Chesterbrook for a period of five years.