Weiser defends birthright citizenship in Supreme Court brief

Feb. 26, 2026 (DENVER) – Attorney General Phil Weiser joined a multistate coalition today on a brief defending birthright citizenship at the U.S. Supreme Court, standing up to President Trump’s illegal effort to rewrite the Constitution and overturn federal law.

On his first day in office in 2025, President Trump issued an executive order to end birthright citizenship for countless children born in the United States to immigrant parents, in violation of the Fourteenth Amendment of the U.S. Constitution and Section 1401 of the Immigration and Nationality Act. Groups of states immediately filed two lawsuits challenging the order, one in the Western District of Washington (PDF) and one in the District of Massachusetts (PDF). Both suits were successful, repeatedly obtaining nationwide preliminary injunctions that blocked this executive order from ever taking effect.

The Supreme Court is now considering the validity of this order in a case brought by a class of children who would lose citizenship, Trump v. Barbara. The state attorneys general filed today’s brief to explain how this executive order violates the Citizenship Clause, binding Supreme Court decisions, and the INA, imposing significant harms on the states and their residents.

“A core promise of our Constitution is that if you are born here, you are citizen,” said Weiser. “That promise is part of our nation’s commitment to e pluribus unum—out of many, we are one. By attempting to undo this promise, President Trump displayed his lack of respect for this tradition, our Constitution, and the rule of law. It is essential that, once again, the Supreme Court act as a check on this President’s lawless actions.”

As the amicus brief explains, the Supreme Court has repeatedly upheld birthright citizenship, regardless of the immigration status of the baby’s parents. In addition, Congress codified birthright citizenship into law twice, first in 1940 and then again in 1952. If allowed to stand, this executive order—for the first time since the Fourteenth Amendment was adopted in 1868—would mean thousands of babies born each year who otherwise would have been citizens will be stripped of their citizenship and lose their ability to fully and fairly be a part of American society as a citizen with all its benefits and privileges. And if the practice were changed, it would impose a significant burden on all parents to demonstrate their citizenship—through a new burden on them—lest their child not be granted citizenship.

In addition to harming hundreds of thousands of residents, the states’ court brief explains that the order significantly harms the states too. Among other things, states will lose federal funding to programs they administer, such as Medicaid, the Children’s Health Insurance Program, and foster care and adoption assistance programs, which depend at least in part on the citizenship status of the resident being served. States will also be required—at considerable expense—to immediately begin modifying their operation and administration of benefits programs to account for this change, which will impose significant burdens on multiple agencies that operate programs for the states’ residents.

Even more alarming, although the order President Trump signed indicates it would only apply to babies born after certain date, there is no reason to believe the Trump administration will stop there if a court sides with its theories. The citizenship of countless Americans could be called into question, including those accorded birthright citizenship decades ago.

The coalition joining today’s filing includes Arizona, California, Colorado, Connecticut, Delaware, the District of Columbia, Hawaii, Illinois, Maine, Maryland, Massachusetts, Michigan, Minnesota, Nevada, New Jersey, New Mexico, New York, North Carolina, Oregon, Rhode Island, Vermont, Virginia, Washington, and Wisconsin, as well as the city of San Francisco.

Read the amicus brief filed in Trump v. Barbara (PDF).

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