WASHINGTON (CN) – The fight for car safety landed in the D.C. Circuit on Wednesday as two nonprofits asked the appeals court to force the Department of Transportation to get moving on making seat-belt warning systems mandatory for backseat passengers. In 2012, Congress required the agency to initiate rulemaking on the matter by Oct. 1, 2014, and implement a final rule one year later. More than three years past the initial deadline and into a new administration, the Center for Auto Safety and KidsAndCars.org say the Transportation Department hasn’t even begun the rulemaking process. Appearing on behalf of the nonprofits, Katherine Meyer argued Wednesday before a three-judge panel that the law only excuses the transportation secretary from meeting the deadlines if the department determines the rule does not meet the requirements that apply to all vehicle safety standards under the Motor Vehicle Safety Act. If that were the case, Meyer said the secretary would need to submit a report to Congress detailing the reasons. The deadline could also be waived if the secretary determines the agency is unable to meet the congressionally mandated deadline, but must notify lawmakers and set a new deadline. “To date – more than three years after being required to do so by Congress – the secretary has not even published a proposed rule for the standard required by the statute,” the nonprofits said in their Oct. 30 petition for a writ of mandamus. Meyer drove that point home Wednesday morning. “Those two years are long gone,” she said. To her knowledge, Meyer said the transportation secretary has not informed Congress of either of the two determinations that would excuse the agency from missing the Oct. 1, 2015 deadline. In the meantime, the nonprofits say that lives are stake, particularly those of children. Pointing to data from the National Highway Traffic Safety Administration, the groups claim nearly half of the roughly 1,500 children killed in car crashes over the last five years were unbuckled. According to their petition, only 3 percent of cars sold in the U.S. have rear seat-belt warning systems, though most cars in Europe and Australia do. But the government says it’s under no obligation to immediately issue a proposed rule, arguing that no legal requirement exists to force the Department of Transportation to implement a rule one year after that. Department of Justice attorney Carleen Zubrzycki argued Wednesday that agency action on the rule is not judicially reviewable. “We think that Congress is best positioned to supervise it,” she said. Zubrzycki also said Congress did not set hard deadlines for the rule, but merely directed the agency to look into the matter and get started. The department says it did initiate rulemaking in 2013 when it solicited public comments on a proposal for a study on the effectiveness of rear seat-belt warning systems. According to the government’s reply brief, the study commenced after the Office of Management and Budget approved it in March 2014. Because of that, Zubrzycki said Wednesday, the Department of Transportation believes it has satisfied the statutory deadlines. She also argued that Congress did not intend to give private citizens the ability to bring a lawsuit to enforce them. The three-judge D.C. Circuit panel wrestled with whether the court has jurisdiction over the matter, and whether a judicially reviewable final agency action exists in the case. U.S. Circuit Judge Patricia Millet pressed Zubrzycki on whether a letter notifying Congress that the agency determined no final rule is possible would constitute a final decision, and if so which court could review it. “We do not think that anybody would have the ability to petition for review of that decision,” Zubrzycki responded. Attorney Meyer had told the court Wednesday morning that the nonprofits brought the case to the D.C. Circuit only after the Department of Justice informed her clients that they originally brought the case in the wrong court. The groups had originally filed an Administrative Procedure Act challenge in the district court on Aug. 17, 2017. Zubrzycki could not say who at the Department of Justice told the nonprofits they had filed in the wrong court, but promised Chief U.S. Circuit Judge Merrick Garland that she would get that information for him. Garland also pressed the attorney to say when the agency sent Congress a letter expressing the need to extend the original deadlines. Zubrzycki noted that the Transportation Department has other ways to communicate with the relevant congressional committees. “All I’m asking is, when did you do that?” Garland retorted, asking if there was a phone conversation that took place that was not entered into the record. Zubrzycki noted that the issue has come up at several congressional oversight hearings, but could not say exactly when. Garland asked her to provide that information to the court at a later time. Garland also pressed Meyer on an unattributed figure in her clients’ petition that claims rear seat-belt warning systems will save nearly 1,000 lives a year. Meyer could not produce the citation on the spot, but said she would look into it. The panel did not say when it would issue an opinion in the case.