AMNA NAWAZ: One of the nation's most conservative appeals courts has struck down a federal law that banned people under domestic violence restraining orders from owning guns.

The decision, which only applies in the fifth district of Texas, Louisiana, and Mississippi, is just part of the massive legal fallout from a U.S. Supreme Court ruling on the Second Amendment last year.

And it could signal how courts will decide on firearms cases for years to come.

Joining me now is Chip Brownlee.

He's a reporter with The Trace, a nonprofit news organization that covers gun violence.

Chip, welcome to the "NewsHour."

Let's just start with the immediate at impact.

So, does this now mean that anyone in Texas or Louisiana or Mississippi who has a domestic violence restraining order can now legally own a gun?

CHIP BROWNLEE, The Trace: This ruling found that the federal law that covers these issues is unconstitutional, but there are still state laws in most of the states that are people who are subjected to domestic violence restraining orders from owning and possessing guns.

And this doesn't immediately affect those state laws.

But in regards to the federal law in those three states, yes, it does - - it does find it unconstitutional.

And, in this case, they vacated a person's sentence who had been -- or vacated the conviction of a person who had been convicted under this law.

AMNA NAWAZ: So the reason those laws were in place in the first place, we should note, there's a well-established connection between domestic violence and gun violence, right?

Tell us about that.

CHIP BROWNLEE: Probably about a fourth of the homicides that are done with guns in the United States are in some way related to domestic violence or family violence.

About half of the women in the U.S. who were shot and killed with a gun every year are shot and killed in domestic violence incidents.

We know from the research that having a gun in a situation raises the risk of a domestic violence murder by about 400 percent.

So, these laws, these were tried to kind of prevent those by having in place a prohibition on a person having a gun if they're under these restraining orders, because you can imagine, if somebody goes to the length to get a restraining order, they feel like they're under an emergency situation, that they need protection.

And those are probably the most dangerous situations that somebody could be.

AMNA NAWAZ: It's notable in their decision they made clear that the question wasn't about whether keeping a gun away from someone who has a domestic violence restraining order is what they call a laudable goal.

They acknowledge it is, but they say they're working under a new standard.

That's a standard that's based on that Supreme Court decision in June known as the Bruen decision.

What did that change?

CHIP BROWNLEE: So, previously, in federal court cases, courts could weigh the benefits of a law against the constitutional questions around it.

So they could look at something and say, this law is designed to prevent gun violence, and it balances that with constitutional protections, and so it can be ruled OK. After Bruen last year, the Supreme Court essentially told lower federal courts that the only thing that they can take into account is history and tradition.

Basically, what they said is, if a law wasn't around, around the time of the founding, around the colonial period, the early days of the U.S., then it can't exist today.

So they basically told the lower courts that they can't consider these other things like public safety.

AMNA NAWAZ: Yes, I found this line really striking, Chip.

In applying the new standard, they say the law is -- quote -- "an outlier that our ancestors would never have accepted."

So they're essentially saying, what, because domestic violence wasn't a crime in the 18th and 19th centuries, then this law is unconstitutional?

CHIP BROWNLEE: Pretty much, yes.

I mean, that's what the Supreme Court told the lower courts to do.

They had to look and see whether there were what's called historical analogies back in the earlier history of America to support a law existing now.

And in the case of domestic violence, most states didn't start criminalizing domestic violence until the 1900s.

And in this specific case, this law, the law that we're talking about, wasn't around until the 1990s.

And so this is not an unreasonable or crazy interpretation of Bruen, considering that there really isn't a historical precedent going back too far for this type of law.

AMNA NAWAZ: What does this new standard mean for all gun laws, all gun restrictions in America?

CHIP BROWNLEE: We really don't know yet.

But I imagine that pretty much any gun law you can think of is going to be challenged under Bruen.

This is the biggest decision since Heller in 2008.

So pretty much anything is up for play.

Right now, we're seeing challenges over things like assault weapons bans.

We're seeing challenges over and rulings already in cases like whether somebody who uses illegal drugs can possess a gun.

There's a split and district courts over that question.

There's also some challenges going on right now over whether somebody who's under felony indictment is allowed to possess gun, because -- possess guns, because, under current federal law, if you're under felony indictment, then you're not allowed to possess guns.

So there was already some district court rulings that said that that's unconstitutional.

So I think we're going to see pretty much any federal gun law, state gun law that you can think of challenged under the Bruen framework.

And if it didn't exist back in the 1800s and 1700s, then it probably could likely be ruled unconstitutional.

AMNA NAWAZ: What about in this specific case?

What are the next steps here?

Is this likely to be appealed by the Department of Justice?

CHIP BROWNLEE: Yes.

So, the Department of Justice has said that they're going to challenge this.

Exactly how that's going to work out kind of remains to be seen.

This was heard by a panel of judges in the Fifth Circuit, so it's possible they could try to get the and full Fifth Circuit to rehear this case, or they could try to directly appeal it to the Supreme Court.

And there are still so many questions over how to apply the Bruen tests and, frankly, what judges are supposed to consider history and what they can consider tradition, that this is going to have to end up back at the Supreme Court.

AMNA NAWAZ: All right, that is Chip Brownlee, reporter with The Trace, a nonprofit news organization that covers gun violence.

Chip, thank you for joining us.

CHIP BROWNLEE: Thank you so much for having me.