Elena, we’ll call her, is Rio Grande Valley lawyer Efrén Olivares’ “favorite” client. Elena works whenever she can, harvesting cotton, onions—whatever’s in season—in South Texas. When there’s “no picking,” says Olivares, Elena cleans houses.

“She’s incredibly resourceful,” Olivares told Rewire.

Elena came to Texas from Mexico years ago. She’s undocumented. So is her infant daughter. But Elena’s baby is a United States citizen—as much an American as anyone else born on U.S. soil.

Elena is one of more than a dozen Texas parents who live in the Rio Grande Valley and who say their children have been wrongly denied birth certificates by the state’s vital statistics unit and therefore discriminated against because of their parents’ immigration status. Eighteen South Texas parents in May filed suit in federal court hoping to get the documentation to which their U.S.-born kids have a right, and which they need in order to enroll in school and to receive civic services.

Some, said Olivares, even need their kids’ birth certificates so they can get a proper baptism.

At issue is the matricula consular, a piece of photo identification issued by the Mexican consulate to Mexican-born residents of the United States. It looks a lot like a drivers’ license, and its use and acceptance has been hotly debated by law enforcement, anti-immigration groups, and conservatives, who question the Mexican government’s ability and willingness to verify the identities of the Mexican nationals to whom it issues the cards.

For her older child, Elena was able to show her matricula consular to the local authorities and obtain a birth certificate, establishing her relationship to her child along with her child’s U.S. citizenship.

“Even though [Olivares’ clients] have social security for the kid, all the hospital records that prove without a doubt the child was born here in Texas,” Olivares said, “the representatives from the vital statistics unit which are located at city hall in various cities are refusing to issue those birth certificates to the parents, claiming that they don’t have the necessary ID documents.”

Elena and her co-plaintiffs say that sometime last year—around and after the time that a wave of undocumented children arrived in Texas—local authorities, under the direction of the Texas Department of State Health Services (DSHS), stopped accepting the consular IDs even though, according to the plaintiffs, they’d accepted it for years.

The plaintiffs’ older children, according to court documents, are proof of that. The older kids have birth certificates. The infants—including Elena’s new baby, born last fall—don’t.

“The timing is a little interesting,” Olivares said. “Right after the influx of many immigrant children last summer, right around [the] time the president announced DACA and DAPA.”

President Obama in November 2014 announced an expansion of DACA, or Deferred Action for Childhood Arrivals, which allows immigrants who arrived in the United States as children to temporarily defer deportation and get work permits, along with a DAPA program expansion for parents. Those expansions are now held up in federal court.

But a representative for DSHS told Rewire via email that the department has long had a policy not to accept the consular cards.

“The Vital Statistics Unit (formerly Bureau of Vital Statistics) has never considered consular IDs to be an acceptable form of ID to obtain copies of vital records,” said DSHS press officer Chris Van Deusen. “That policy has been applied uniformly by DSHS. We can’t speak to how it has been applied by local registrars.”

The Texas attorney general has responded to the lawsuit by asking the Western District court to dismiss the suit entirely, claiming that the federal government has no right to dictate to Texas the terms of its policy for issuing birth certificates to U.S. citizens, essentially making a “states’ rights” argument that echoes Texas leaders’ opposition to legalizing gay marriage.

The plaintiffs, argue the attorney general, have no legal standing to bring a complaint against the state or its employees.

Elena and her co-plaintiffs—on behalf of their children, who are not identified by name in the suit—argue that their U.S. citizen kids are entitled to equal protection under the 14th Amendment, which prohibits discrimination on the basis of national origin.

They say that local entities, which operate under the direction of DSHS, have stopped accepting matricular, and that because of the restrictions on forms of identification the vital statistics unit will accept, they can’t fulfill the requirements to get their kids’ records.

Olivares said that many Mexican and Central American immigrants—his clients—were told by the coyotes who charge large sums to guide immigrants across the border that they should throw away their drivers’ licenses and other identification documents before they cross the Rio Grande River.

When they arrive in Texas, they arrive wholly without identification.

And now that these immigrants have built lives in Texas, working and raising families, their U.S.-born children lack access to the documents that children of U.S.-born parents can more easily obtain.

In order to secure a birth certificate, a parent can present one form of “primary” identification or two forms of “secondary” identification. The list of acceptable primary forms of ID are, in Texas, unavailable to undocumented people. The acceptable “secondary” forms of identification largely present the same challenge, though state statute says that “foreign identification with identifiable photo of applicant” is acceptable.

But not, according to DSHS officials, the matricular, despite the fact that it is a foreign identification with an identifiable photo of an applicant.

Van Deusen told Rewire that DSHS does not accept consular IDs because “the documents used to obtain the matricula are not verified by the issuing party.”

Olivares’ clients are not only challenging DSHS and the local registrars’ denial of birth certificates to the plaintiffs’ children, but are also challenging the state’s policy of not accepting the consular IDs themselves, and asking for clarification as to what identification undocumented parents can use to get their kids’ certificates.

Olivares told Rewire that his goal is to “first of all, to get birth certificates for these children and second, to get a clearer guidance from vital statistics unit to clarify what they will require of undocumented parents who have U.S. citizen children.”

Even if the vital statistics unit concedes to issuing birth certificates to the named plaintiffs’ kids, Olivares said, his office hears from more and more parents dealing with this problem every day.

So far, all of his clients live in the Valley area, but they’re already getting calls from parents along the border toward Laredo and West Texas, and Olivares says he and his colleagues expect to add more plaintiffs to the suit in the coming weeks.