A federal appeals court has upheld the dismissal of a lawful permanent resident’s challenge to a federal rule imposing an age limit on children of immigrants gaining citizenship based on their parents’ status.

The U.S. Court of Appeals for the Third Circuit affirmed a district court’s denial of Carmen Josefina Contreras Aybar’s Immigration and Nationality Act challenge to a Department of Homeland Security regulation cutting off permanent-resident status for children of immigrants at age 21.

According to Third Circuit Judge Thomas Ambro’s opinion, Aybar began the application process for her son one day before his 21st birthday. Homeland Security initially granted her petition, but then revoked it because her son, Dario, was deemed overage.

Aybar then filed a complaint in district court, arguing that Homeland Security overstepped its authority and that its decision was “arbitrary and capricious.” U.S. District Judge Esther Salas of the District of New Jersey sided with the government.

Among their arguments, Aybar and her son claimed that a reading of 8 U.S.C. §1255(m)(3) to mean that children can be “aged-out” is “absurd.”

Aybar argued that “It would put child applications at the whim of agency processing times, over which applicants have absolutely no control,” Ambro summarized. “It also would make it impossible to predict a child’s eligibility under the statute at the time of filing an application. And it would mean that two identically situated children—twin children of a woman who obtains U-1 immigrant status, for example—might be denied or granted LPR status based purely on how quickly DHS processes their separate applications.”

Ambro said Aybar’s arguments carried weight, but remained unpersuasive.

“There is heft to these arguments and, were we writing on a blank slate, we may well be swayed. But, unfortunately, we are not because Congress and the Supreme Court do not appear to view ‘aging out’ of immigration benefits as an absurdity,” Ambro said.

“Congress made that viewpoint clear in, among other laws, the Child Status Protection Act, which protects certain categories of children from aging out of immigration benefits while their applications are pending,” he wrote. “The incomplete coverage of that Act implies Congress knows but has not addressed when children not protected by it may still be subject to aging out of eligibility due to the vagaries of the application process.”

Ambro pointed to the U.S. Supreme Court’s 2014 decision in Scialabba v. Cuellar de Osorio, in which the high court mentioned the possibility of aging out under the rules.

Joshua Cohn of Davis Polk & Wardwell in New York represented the plaintiffs and did not respond to a request for comment.

The Department of Justice also did not respond to a request for comment.