AMNA NAWAZ: Today, the American Civil Liberties Union sued the Trump administration over the president's executive order targeting gender-affirming care for minors.

The lawsuit says Trump's actions -- quote -- "unconstitutionally usurp congressional authority by withholding lawfully appropriated federal funds" and violate the rights of trans youth by - - quote -- "depriving them of necessary medical care solely on the basis of their sex and transgender status."

Our White House correspondent, Laura Barron-Lopez, has been covering this and joins us now.

So, Laura, just lay out the scope for us of the president's executive order and what's happened since it was signed.

LAURA BARRON-LOPEZ: Last week, President Trump signed an executive order targeting gender-affirming care for minors.

And that action states that the federal government will not fund, sponsor, promote, assist, or support the so-called transition of a child from one sex to another.

And we should note that that order defines child as anyone under the age of 19, which includes legal adults in many states.

The order also threatens to withhold federal funding from hospitals or institutions that may also happen to provide gender-affirming care.

And that's led some providers, even in states that protect this kind of care, to suspend it.

Children's National in D.C. said that it is pausing all puberty blockers and hormone treatment prescriptions for youth.

Reports of similar moves are also in Colorado and New York, which led New York Attorney General Letitia James, she told providers that canceling care would violate state law.

We should note, Amna, that gender-affirming care is endorsed by the majority of major U.S. medical associations, including the American Academy of Pediatrics.

AMNA NAWAZ: I know you have been talking to a family in Texas who says they're feeling an immediate impact.

What are they telling you?

LAURA BARRON-LOPEZ: A couple of years ago, we interviewed a Texas family, John, Mary, and their now 14-year-old trans daughter, Leah.

We have changed their name to protect their identity.

And after Texas banned gender-affirming care for minors, they started going to New Mexico for treatment.

We spoke to John and Mary again today.

And since the executive order, they say that they haven't been able to get ahold of their doctor in New Mexico.

They were actually planning to try to move to Colorado, one of the states that supports and provides gender-affirming care for minors.

But Leah had her -- Leah had her bags packed and was ready to go, but now they say that the signals from Colorado are murky, and it's unclear if they're going to continue to provide treatments.

And here's John.

JOHN, Father of Leah: It was definitely going to be just a safer move.

And to be in a place where our daily lives just felt safe and accepted was worth the effort to do that move.

But now, with these executive orders, he's already talked about going after sanctuary states if they don't comply with his orders.

So we're kind of now in this weird floating place where, yes, we want to get out of here, but can we really go anywhere we're going to be safe?

LAURA BARRON-LOPEZ: Leah's parents told us that she has enough medication -- that's puberty blockers and hormone treatment -- to last until about June, but they don't know what may happen after that, Amna.

AMNA NAWAZ: Laura, back it up here.

What is the White House argument for this executive order, and what is the ACLU saying their legal argument is to challenge it here?

LAURA BARRON-LOPEZ: The White House claims that this is about protecting children, and they have increasingly described gender-affirming care in graphic and sometimes disdainful terms, calling it -- quote -- "chemical castration" and -- quote -- "mutilation."

And it's important to fact-check that treatments like puberty blockers are commonly used and are reversible, and gender-affirming care for minors is rare.

All gender-affirming care treatments are part of extensive evaluations between doctors and families.

But the White House's main argument here is that, with this action and other sweeping actions that they have taken so far, they say that the president has the authority to stop funding from going to anything that they believe is against or the opposite of the president's ideological agenda.

Now, we spoke to Chase Strangio, who's an attorney at ACLU, who argues the opposite.

CHASE STRANGIO, American Civil Liberties Union: President Trump simply does not have the authority to attempt to cut off federal funding for institutions that provide medical care for transgender adolescents and that he is directing his federal agencies to violate federal law that in fact protects the provision of this care.

We're also arguing that these attempts to restrict care violate the individual constitutional rights of transgender adolescents and their parents.

LAURA BARRON-LOPEZ: Now, Chase said that their argument also is saying that the transgender people are protected under the equal protection rights clause against discrimination based on sex, and this is also about due process rights of parents.

And I should note, Amna, that I accidentally said that gender-affirming care for minors is rare.

It's gender-affirming care surgery for minors is incredibly rare.

AMNA NAWAZ: Thank you for that important clarification, but a broader look here now.

When you look at the rights of transgender people, where does this move from the Trump administration fit into any broader pattern that we have seen?

LAURA BARRON-LOPEZ: Trump's actions have been very sweeping when it comes to trying to dismantle some transgender rights.

That includes instructing the government to acknowledge only two genders, moving trans women to men's prisons, directing the DOD to reinstitute the trans military ban, and stopping social transitioning in schools.

And, tomorrow, we are expecting that the president will sign another executive action that would ban trans athletes from playing on girls and women's school sports teams, Amna.

AMNA NAWAZ: Laura Barron-Lopez, thank you.

LAURA BARRON-LOPEZ: Thank you.