Hundreds of parents whose children were removed from them by county authorities are demanding changes to Minnesota's child welfare laws, arguing that they are unconstitutionally broad and tear families apart.

On the opening day of a federal lawsuit against the state, about 200 parents and their children gathered in front of the federal courthouse in St. Paul to protest what they claim are systemic racism and unnecessary investigations by child protection agencies.

The civil rights case, if allowed to go forward, could test the ability of county child protection agencies to respond to reports of child maltreatment, while raising broader questions about what constitutes child abuse.

In opening statements Tuesday morning, attorneys for the parents said they want stronger protections for parental rights and the right for parents to use corporal punishment to discipline their children. They argue that Minnesota laws are "unconstitutionally vague" by failing to specify a threshold of harm before children are removed from their parents. That deprives families of due process under the U.S. Constitution and wrongly criminalizes parents for ordinary discipline such as spanking, according to the lawsuit.

"There is a lot of trauma from these separations," said Erick Kaardal, an attorney representing the parents. "There has to be a standard … [Removing a child] has to be connected to substantial harm."

In a legal brief, attorneys for the state argued that while parents have a fundamental right to the care and custody of their children, that right has never been interpreted by the courts to include the right to inflict harm. The U.S. Supreme Court has repeatedly upheld state child protection laws and implicitly rejected a right to corporal punishment, on the basis that the state has a compelling interest in protecting children from harm.

"All persons have a fundamental right to bodily integrity, a notion fundamentally at odds with the plaintiffs' claimed right to use corporal punishment that injures a child," the Minnesota Attorney General's Office argued in a motion to dismiss the lawsuit.

The state Department of Human Services, which oversees child protection, said in a statement: "It is always a hard situation when courts or county social workers remove children from their parents' custody. That difficult decision is based on the individual facts of the case and the needs of the children."

Children are often reunited with their parents, the agency said, "once judges, social workers and other professionals complete a thorough evaluation and determine reunification is safe and in the best interests of kids, parents and children."

Still, many parents say the removals unfairly target people with few resources and frequently result in black children being placed with white foster parents, cutting them off from their heritage and community.

They point to 2016 state data showing that African-American children are more than three times more likely than white children to be reported to child protection and removed from their homes. American Indian children were nearly 18 times more likely to be removed than white children.

The parents also argue that county child protection agencies across the state have become overly aggressive in recent years, seizing children as a safety precaution without clear evidence of abuse.

In 2014, in the wake several high-profile failures of the system — including the murder of 4-year-old Eric Dean by his stepmother despite 15 child-abuse reports filed on his behalf — child protection agencies revamped their practices for "screening in" maltreatment cases for review, which led to a dramatic surge in caseloads. The number of reports screened-in for review has surged from 20,167 reports in 2014 to 30,936 in 2016, according to a state report.

22 months away

The lead plaintiff in the lawsuit, Dwight Mitchell, 57, alleged that Dakota County child protection workers in 2014 took custody of his three children after a babysitter reported that his 11-year-old son received a spanking for repeated acts of disobedience. The child was kept in state custody for 22 months and was denied all contact with his father. Mitchell's other two children were removed for five months, according to the lawsuit.

"It was 22 months of lost smiles, lost hugs and lost time spent together as a family," Mitchell alleged.

In 2014, Mitchell was convicted of two counts of malicious punishment of a child in connection with the alleged abuse. According to a Dakota County criminal complaint, police observed large bruises on his son's arms, as well as linear marks consistent with the child being struck with a belt. The boy told police that he was in his bedroom using his phone when Mitchell threw the child's phone against the wall, punched him, and then removed his belt and struck the child's arm and hip. Another of Mitchell's children, who was 6, said Mitchell struck him "approximately sixteen times" with the belt, according to the criminal complaint.

Mitchell defended his actions, saying it amounted to "ordinary discipline that I, and everyone I knew growing up, had all experienced."

An organization founded by Mitchell said it has found more than 500 cases in about 40 counties where children were wrongly removed from their homes and placed in foster care based on false or disputed evidence. The group, called the Family Preservation Foundation, has swelled to nearly 5,000 members statewide since the lawsuit was filed in April.

U.S. District Judge Wilhelmina Wright is expected to rule within 90 days on whether the lawsuit will go forward or be dismissed.