Two Maryland parents whose hands-off 'free-range' parenting got their children picked up by police yet again on Sunday are now vowing to file a lawsuit. Danielle and Alexander Meitiv have been cited multiple times for allowing their son Rafi, 10, and daughter Dvora, 6, roam free in their suburban neighborhood. But the Meitivs, both of them scientists, say authorities crossed a line over the weekend when they picked up Rafi and Dvora and held them nearly six hours without food before allowing them to reunite with their parents. Picked up: Officials seized Dvora, 6, (far left) and 10-year-old Rafi (left, blue hat) on Sunday in a Maryland park. The parents Danielle and Alexander Meitiv (right) have vowed to sue authorities responsible for keeping them in custody for six hours . Attorney Matthew Dowd, of the firm Wiley Rein, is representing the Meitivs and on Tuesday sent a ointed letter regarding Sunday's events. Rein wrote: . 'The actions of Maryland CPS and Montgomery County Police violate the fundamental rights parents have in raising their children. 'This fundamental, constitutional right of parents cannot be infringed simply because certain governmental employees disagree with a parent’s reasoned decision on how to raise his or her children.' The firm declined to say who the suit would be against, exactly, when asked by the Washington Post. However, the attorney has vowed to pursue 'all legal remedies' to protect the rights of the Maryland parents. The Meitivs made headlines just before Christmas when police found Rafi and Dvora walking the sidewalk on their own. Picked up AGAIN: The Meitivs say they were left to panic for hours by CPS workers after their children--who they raise with a so-called 'free-range' approach--were picked up by police for the second time in two months while walking down the street alone . 'Besides the policeman pulling up...no': Asked if he was scared during the hours-long ordeal Sunday, 10-year-old Rafi admitted he was, but not because he'd been left alone with his sister . Free-range parenting is the name given to a style of raising kids in opposition to so-called 'helicopter parenting'. 'Helicopter parents' are named for their habit of hovering over their offspring, micro-managing their lives in an attempt to keep them safe. However critics believe this creates under-confident, over-reliant children, while also causing the parents stress. Free-range parents advocate a more hands-off approach, where children are allowed to go out and experience the world on their own. Instead of constantly monitoring activities to make sure children are safe, the emphasis is put on adults assessing risk ahead of time, and equipping children with the skills to deal with danger themselves. On Sunday, a concerned citizen reportedly called authorities once again after seeing the siblings unaccompanied near a neighborhood park around a third of a mile from their home. The children were picked up by police, who say they followed protocol by turning them over to CPS. Meanwhile, Mrs Meitiv tells Fox 5 DC that CPS workers left her and her husband to panic for hours before letting them know their kids were safe. What's more, the elder child, Rafi, insists the scariest part of the hours-long ordeal was being picked up by police. ‘They kept the kids for hours,’ a shaken Danielle Meitiv told Fox 5 after being reunited with them. ‘It’s 10:30 at night. They’ve been missing since 6 o’clock…Somebody called 911 and the police called CPS and they decided to bring the kids here and they didn’t call us.’ According to Mrs. Meitiv, the children were expected home no later than 6:30. When 6:30 came and went, they became frantic. They would not receive a call from CPS until 8pm. Even then, they say they weren't reunited with their children or even told where they were for hours. in the interim, Rafi tells Fox 5 that initially he believed the responding police officer was simply offering them a lift. Rafi said: . ‘The policeman said “We’ll give you a ride home” when we were like two blocks away. And two and a half hours later, after sitting in the car two and a half hours, he said “I’ll bring you home” and, instead, he brought us here.’ 'Here' was Child Protective Services, Rafi said. And as he and his sister sat waiting to go home, their parents say 'upper management' at CPS was involved in keeping that from happening. Only at 10:30pm did Mrs. Meitiv say she was reunited with her children and only after promising not to let them off the leash. Parenting style: The Meitivs believe in giving children an unusual amount of independence from a young age . Guarantees: As part of their free-range parenting philosophy, the Meitivs make sure their children carry these badges in case someone worries and asks while they are out on the street . ‘They made us sign a safety plan that says we will not leave them attended at all until they follow up, . 'And I’m not gonna risk my kids being snatched again like this by CPS.' When questioned, the Meitivs say they believe in a so-called 'free-range' approach to parenting, which encourages independence from infancy. In March, the CPS found the couple guilty of neglect for letting the children walk home from school alone. It meant the agency would start a file on the family's activities and whereabouts for at least five years. The Meitivs hit back at the ruling, insisting they would continue to bring up their own children as they see fit - whatever the consequences. Unsubstantiated child neglect is not a criminal charge, but is in most cases a prelude to such charges. It usually comes when the CPS has deemed parents to have neglected their children, but has insufficient information or witnesses to press charges or take action.
Police seized Rafi, 10, and Dvora, 6, in a Maryland park on Sunday and their parents say they weren't reunited by CPS for hours .
Scientists Danielle and Alexander Meitiv believe in 'free range parenting' meaning the children are afforded total independence from infancy .
The Meitivs were found guilty of neglect in March. After Sunday's incident they were forced sign a paper pledging not to leave them unattended .